SYSTEMS AND METHODS FOR ONE-SHOT GUIDE RNA (ogRNA) TARGETING OF ENDOGENOUS AND SOURCE DNA

ABSTRACT

Engineered nucleic acids encoding genome editing system components are provided, as are engineered RNA-guided nucleases that include inserts encoded in part by cellular genomic or other sequences recognized by guide RNAs.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.15/832,567, filed Dec. 5, 2017, which claims priority to U.S.Provisional Application No. 62/430,154 filed on Dec. 5, 2016, and toU.S. Provisional Application No. 62/503,640 filed on May 9, 2017, thecontents of each of which are incorporated by reference in theirentireties, and to each of which priority is claimed.

SEQUENCE LISTING

This application contains a Sequence Listing, which was submitted inASCII format via EFS-Web, and is hereby incorporated by reference in itsentirety. The ASCII copy, created on Mar. 23, 2018, is named0841770179SEQLISTING.TXT and is 93,012 bytes in size.

FIELD

This disclosure relates to genome editing systems and related methodsand compositions for editing a target nucleic acid sequence, ormodulating expression of a target nucleic acid sequence, andapplications thereof. More particularly, the disclosure relates toengineered self-regulating genome editing systems.

BACKGROUND

CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats)evolved in bacteria and archaea as an adaptive immune system to defendagainst viral attack. Upon exposure to a virus, short segments of viralDNA are integrated into the CRISPR locus. RNA is transcribed from aportion of the CRISPR locus that includes the viral sequence. That RNA,which contains sequence complementary to the viral genome, mediatestargeting of a Cas9 protein to a target sequence in the viral genome.The Cas9 protein, in turn, cleaves and thereby silences the viraltarget.

Recently, the CRISPR/Cas system has been adapted for genome editing ineukaryotic cells. The introduction of site-specific double strand breaks(DSBs) allows for target sequence alteration through endogenous DNArepair mechanisms, for example non-homologous end-joining (NHEJ) orhomology-directed repair (HDR).

The use of CRISPR/Cas-based genome editing systems as a tool for thetreatment of inherited diseases is widely recognized. The U.S. Food andDrug Administration (FDA), for example, held a Science Board Meeting onNov. 15, 2016, addressing the use of such systems and potentialregulatory issues they may pose. In that meeting, the FDA noted thatwhile Cas9/guide RNA (gRNA) ribonucleoprotein (RNP) complexes may becustomized to generate precise edits at a locus of interest, thecomplexes may also interact with, and cut at, other “off-target” loci.The potential for off-target cuts (“off-targets”), in turn, raises atleast a regulatory risk with respect to approval of CRISPR/Castherapeutics.

One strategy for reducing off-target risk is to include, in a vectorencoding a Cas9, a “governing guide RNA,” (ggRNA) which is a guide RNAtargeted to the Cas9 coding sequence. When this vector is delivered to asubject, Cas9, which might otherwise be constitutively and/or stablyexpressed by virally transduced cells, is expressed only transiently.Over time, the Cas9 coding domain in the vector is disrupted by cuttingmediated by the governing guide RNA.

SUMMARY

The instant disclosure provides genome editing systems and relatedmethods which adapt gRNAs targeted to specific loci to temporally limitthe genome editing activity of these systems in a manner distinct fromconventional ggRNAs. These adapted gRNAs are referred to as “one-shotguide RNAs” or “ogRNAs”. For clarity, ogRNAs described herein can beunimolecular or modular, as discussed in greater detail below.Adaptation of gRNAs into ogRNAs is achieved by engineering cellular DNAsequences recognized by such gRNAs into nucleic acid sequences encodingan RNA-guided nuclease, e.g., a Cas9 nuclease or a Cpf1 nuclease or avector backbone. In certain embodiments, the RNA-guided nuclease isCas9. In certain embodiments, the RNA-guided nuclease is Cpf1.

In one aspect, this disclosure relates to an isolated nucleic acidencoding an RNA-guided nuclease, which isolated nucleic acid includesan, exogenous, substituted, inserted or engineered nucleic acidsequence, such as a eukaryotic nucleic acid sequence. The eukaryotic orotherwise exogenous sequence is generally 17 nucleotides or greater inlength, and either comprises or is adjacent to a protospacer adjacentmotif (PAM) that is recognized by the RNA-guided nuclease. Certainembodiments of the isolated nucleic acid also encode a gRNA (forinstance, an ogRNA) having a targeting domain that is complementary to aportion of the exogenous or eukaryotic nucleic acid sequence that isadjacent to the PAM, which targeting domain is optionally greater than16 nucleotides or 16-24 nucleotides in length. In certain embodiments,the complementarity of the targeting domain to a portion of theexogenous or eukaryotic nucleic acid sequence is sufficient to allow formodification of the nucleic acid sequence encoding the RNA-guidednuclease. In certain embodiments, the targeting domain is complementaryto at least about 50%, about 60%, about 70%, about 80%, about 90%, about91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%,about 98%, about 99% of the exogenous or eukaryotic nucleic acidsequence. In certain embodiments, the RNA-guided nuclease is a Cas9protein. In some embodiments, the eukaryotic nucleic acid sequence iswithin an RNA-guided nuclease coding sequence, where it can encode atleast part of a modified portion of the protein. In instances whereinthe exogenous sequence encodes all or part of a modified portion of theRNA-guided nuclease, that sequence can be positioned within a regionthat is flanked by codons for glycine, alanine or valine at each of its3′ and 5′ ends. In some cases, the region of the RNA-guided nucleasecoding sequence comprising the exogenous nucleic acid sequence encodesan amino acid having a sequence of G-(X)₆₋₁₀-G. In embodiments where theRNA-guided nuclease is Cas9, the proteins encoded by these sequences cancomprise insertions (relative to SEQ ID NO: 2) such asE271_N272insGX₆₋₁₀G, L371_N372insGX₆₋₁₀G, and/or Q737_A738insGX₆₋₁₀G,and/or insertions at or near the N-terminus of a Cas9 peptide, and/orsequences of at least 95% identity (e.g. 95%, 96%, 97%, 98%, 99% orgreater identity) to SEQ ID NOS: 3-5 and 10.

Continuing with this aspect of the disclosure, the isolated nucleic acidcan include an insertion (relative to SEQ ID NO: 6) c.813_814insN27-36,c.1113_1114insN27-36, and/or c.2211_2212insN27-36, and/or insertions ator near the coding sequence of the N-terminus of a Cas9 peptide, and/orhave at least 95% (e.g. 95%, 96%, 97%, 98%, 99% or greater identity)sequence identity to SEQ ID NOS: 7-9 and 11. The isolated nucleic acidcan, alternatively or additionally include an insertion ofc.157insN₁₉₋₃₆ and/or share at least 80% (e.g. 80%, 85%, 90%, 95%, 96%,97%, 98%, 99% or greater identity) sequence identity with SEQ ID NO: 1.Isolated nucleic acids according to this aspect of this disclosure areoptionally incorporated into vectors such as plasmids, viral vectors,naked DNA vectors, etc. In some instances, an adeno-associated virus(AAV) vector incorporates isolated nucleic acids according to thisaspect of the disclosure. In certain embodiments, a target site for thegRNA is within the vector backbone. The vectors can be used to alterboth a cellular endogenous target gene and the RNA-guided nucleaseexpression.

In certain embodiments, the RNA-guided nuclease is Cpf1. In certainembodiments, the amino acid sequence of a Cpf1 protein is set forth inSEQ ID NO: 13. In certain embodiments, the Cpf1 protein can comprise aninsertion such as a GX₆₋₁₀G insertion. In certain embodiments, theinsertion (relative to SEQ ID NO: 13) is positioned between amino acidpositions 147 and 148, anywhere between amino acid positions 484 and492, anywhere between amino acid positions 568 and 590, anywhere betweenamino acid positions 795 and 855, anywhere between amino acid positions1131 and 1140, or anywhere between amino acid positions 1160 and 1173.In certain embodiments, the insertion is positioned at or near theN-terminus of a Cpf1 peptide. In certain embodiments, the amino acidsequence of the Cpf1 protein comprising the insertion has at least 95%sequence identity (e.g. 95%, 96%, 97%, 98%, 99% or greater identity) toSEQ ID NO: 13.

In certain embodiments, an isolated nucleic acid sequence encoding aCpf1 protein is set forth in SEQ ID NO: 14. In certain embodiments, theisolated Cpf1 nucleic acid can comprise an insertion such as an N24-36insertion. In certain embodiments, the insertion (relative to SEQ ID NO:14) is positioned between nucleic acid positions 441 and 442, anywherebetween nucleic acid positions 1452 and 1474, anywhere between nucleicacid positions 1704 and 1768, anywhere between nucleic acid positions2385 and 2563, anywhere between nucleic acid positions 3393 and 3418, oranywhere between nucleic acid positions 3480 and 3517. In certainembodiments, the insertion does not alter the reading frame of theisolated Cpf1 nucleic acid. In certain embodiments, the insertion ispositioned at or near the N-terminus of a Cpf1 peptide. In certainembodiments, the nucleic acid sequence of the Cpf1 protein comprisingthe insertion has at least 95% (e.g. 95%, 96%, 97%, 98%, 99% or greateridentity) sequence identity to SEQ ID NO: 14. Isolated nucleic acidsaccording to this aspect of this disclosure are optionally incorporatedinto vectors such as plasmids, viral vectors, naked DNA vectors, etc. Insome instances, an adeno-associated virus (AAV) vector incorporatesisolated nucleic acids according to this aspect of the disclosure. Incertain embodiments, a target site for the gRNA is within the vectorbackbone. The vectors can be used to alter both a cellular endogenoustarget gene and the RNA-guided nuclease expression.

In another aspect, the disclosure relates to transiently active genomeediting systems that include a guide RNA with a targeting domain that iscomplementary to a eukaryotic nucleotide sequence and an engineeredRNA-guided nuclease encoded by a nucleic acid comprising a eukaryoticnucleic acid sequence as described above. In certain embodiments, theRNA-guided nuclease is a Cas9 protein. The gRNA and engineered Cas9 canform a Cas9/gRNA complex, which complex may in turn cleave or otherwisealter or inactivate the nucleic acid encoding the engineered Cas9protein. In certain embodiments, the Cas9/gRNA complex can cleave anucleic acid encoding a cellular endogenous target gene. The transientlyactive genome editing system can be used to alter both the cellularendogenous target and the RNA-guided nuclease expression. As discussedabove, the eukaryotic nucleic acid sequence can encode, at least inpart, a modified portion (e.g., amino acid insertion or substitution) ofthe Cas9, which modified portion has a sequence as described above. Incertain embodiments, the engineered Cas9 protein has at least about 80%nuclease activity of a wild-type Cas9 protein.

In certain embodiments, the RNA-guided nuclease is a Cpf1 protein. ThegRNA and engineered Cpf1 can form a Cpf1/gRNA complex, which complex mayin turn cleave or otherwise alter or inactivate the nucleic acidencoding the engineered Cpf1 protein. In certain embodiments, theCpf1/gRNA complex can cleave a nucleic acid encoding a cellularendogenous target gene. The transiently active genome editing system canbe used to alter both the cellular endogenous target and the RNA-guidednuclease expression. As discussed above, the eukaryotic nucleic acidsequence can encode, at least in part, a modified portion (e.g., aminoacid insertion or substitution) of the Cpf1, which modified portion hasa sequence as described above. In certain embodiments, the engineeredCpf1 protein has at least about 80% nuclease activity of a wild-typeCpf1 protein

In yet another aspect, the disclosure relates to a RNA-guided nucleasecomprising an amino acid insertion or substitution at least partiallyencoded by a eukaryotic nucleic acid sequence of at least 17 nucleotidesin length. In certain embodiments, the RNA-guided nuclease having theamino acid insertion or substitution has at least about 80% nucleaseactivity of a wild-type RNA-guided nuclease. The eukaryotic sequence canbe a mammalian sequence, and/or the sequence of a human or animalsubject. In certain embodiments, the RNA-guided nuclease can be a Cas9protein and nucleic acids encoding the Cas9 protein according to thisaspect of this disclosure are substantially as described above.

In another aspect, the disclosure relates to a method of altering a cellthat involves delivering (e.g. contacting, administering, introducing,transfecting, transducing, etc.) a transiently expressed genome editingsystem as described above. In certain embodiments, the method can beused to alter a target site in a cell. In certain embodiments, themethod can be used to alter both a cellular endogenous target gene andthe RNA-guided nuclease expression.

In still another aspect, this disclosure relates to a kit comprising oneor more components of a transiently active genome editing system, anucleic acid and/or an RNA-guided nuclease according to the variousaspects of the disclosure presented above.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are intended to provide illustrative, andschematic rather than comprehensive, examples of certain aspects andembodiments of the present disclosure. The drawings are not intended tobe limiting or binding to any particular theory or model, and are notnecessarily to scale. Without limiting the foregoing, nucleic acids andpolypeptides may be depicted as linear sequences, or as schematic two-or three-dimensional structures; these depictions are intended to beillustrative rather than limiting or binding to any particular model ortheory regarding their structure.

FIG. 1A is a diagram illustrating a SaCas9-gRNA complex targeting bothan endogenous cellular target and a nucleic acid encoding the SaCas9 ina viral vector.

FIG. 1B is a cartoon diagram depicting a 2-vector system in whichengineered SaCas9 and gRNAs are encoded on separate viral genomes. Twotypes of exemplary sites in a recombinant adeno-associated virus (AAV)genome into which heterologous cellular sequences can be engineered aremarked by arrows.

FIG. 2 is a ribbon diagram depicting an S. aureus Cas9 protein.Exemplary regions which can be encoded by engineered heterologoussequences are identified by arrows.

FIGS. 3A-3C are schematic graphs showing exemplary peptide-encodinginserts incorporating heterologous cellular sequences.

FIG. 4A is a cartoon diagram depicting exemplary constructs with targetsites at four different positions in the SaCas9 coding sequence, as wellas a gRNA expression plasmid.

FIG. 4B depicts comparisons of transcription levels and translationlevels of wild-type Cas9 constructs and self-inactivating Cas9constructs.

FIGS. 4C-4E depict the levels of nuclease activity among wild-type andself-inactivating SaCas9 proteins.

FIG. 5A depicts the experimental design in Example 3.

FIG. 5B depicts self-inactivating AAVs maintain efficacy at target GFPplasmids while self-inactivating in HEK293 cells. The upper left panelshows the locations of target sites inserted in the self-inactivatingCas9 constructs. The lower left panel shows GFP expression levels inHEK293 cells with or without wild-type or self-inactivating SaCas9constructs. The lower right panel shows Cas9 protein levels in HEK293cells transduced with wild-type or self-inactivating SaCas9 constructs.

FIG. 6A is a graph showing the editing levels of an endogenous targetlocus (mCEP290) with wild-type or self-inactivating SaCas9 constructs inmouse retinal explants.

FIG. 6B is a graph demonstrating the % wild-type SaCas9 sequence levelsin mouse retinal explants with wild-type or self-inactivating SaCas9constructs.

FIG. 7A depicts the editing levels of an endogenous target locus withwild-type or self-inactivating SaCas9 constructs in vivo.

FIG. 7B depicts the fold changes of specific transcripts expressedthrough self-inactivating SaCas9 constructs compared to the wild-typeSaCas9 construct.

DETAILED DESCRIPTION Definitions and Abbreviations

Unless otherwise specified, each of the following terms has the meaningassociated with it in this section.

The indefinite articles “a” and “an” refer to at least one of theassociated noun, and are used interchangeably with the terms “at leastone” and “one or more.” For example, “a module” means at least onemodule, or one or more modules.

The conjunctions “or” and “and/or” are used interchangeably asnon-exclusive disjunctions.

“Domain” is used to describe a segment of a protein or nucleic acid.Unless otherwise indicated, a domain is not required to have anyspecific functional property.

An “indel” is an insertion and/or deletion in a nucleic acid sequence.An indel may be the product of the repair of a DNA double strand break,such as a double strand break formed by a genome editing system of thepresent disclosure. An indel is most commonly formed when a break isrepaired by an “error prone” repair pathway such as the NHEJ pathwaydescribed below.

“Gene conversion” refers to the alteration of a DNA sequence byincorporation of an endogenous homologous sequence (e.g. a homologoussequence within a gene array). “Gene correction” refers to thealteration of a DNA sequence by incorporation of an exogenous homologoussequence, such as an exogenous single- or double-stranded donor templateDNA. Gene conversion and gene correction are products of the repair ofDNA double-strand breaks by HDR pathways such as those described below.

Indels, gene conversion, gene correction, and other genome editingoutcomes are typically assessed by sequencing (most commonly by“next-gen” or “sequencing-by-synthesis” methods, though Sangersequencing may still be used) and are quantified by the relativefrequency of numerical changes (e.g., ±1, ±2 or more bases) at a site ofinterest among all sequencing reads. DNA samples for sequencing may beprepared by a variety of methods known in the art, and may involve theamplification of sites of interest by polymerase chain reaction (PCR),the capture of DNA ends generated by double strand breaks, as in theGUIDEseq process described in Tsai et al. (Nat. Biotechnol. 34(5): 483(2016), incorporated by reference herein) or by other means well knownin the art. Genome editing outcomes may also be assessed by in situhybridization methods such as the FiberComb™ system commercialized byGenomic Vision (Bagneux, France), and by any other suitable methodsknown in the art.

“Alt-HDR,” “alternative homology-directed repair,” or “alternative HDR”are used interchangeably to refer to the process of repairing DNA damageusing a homologous nucleic acid (e.g., an endogenous homologoussequence, e.g., a sister chromatid, or an exogenous nucleic acid, e.g.,a template nucleic acid). Alt-HDR is distinct from canonical HDR in thatthe process utilizes different pathways from canonical HDR, and can beinhibited by the canonical HDR mediators, RAD51 and BRCA2. Alt-HDR isalso distinguished by the involvement of a single-stranded or nickedhomologous nucleic acid template, whereas canonical HDR generallyinvolves a double-stranded homologous template.

“Canonical HDR,” “canonical homology-directed repair” or “cHDR” refer tothe process of repairing DNA damage using a homologous nucleic acid(e.g., an endogenous homologous sequence, e.g., a sister chromatid, oran exogenous nucleic acid, e.g., a template nucleic acid). Canonical HDRtypically acts when there has been significant resection at the doublestrand break, forming at least one single-stranded portion of DNA. In anormal cell, cHDR typically involves a series of steps such asrecognition of the break, stabilization of the break, resection,stabilization of single-stranded DNA, formation of a DNA crossoverintermediate, resolution of the crossover intermediate, and ligation.The process requires RAD51 and BRCA2, and the homologous nucleic acid istypically double-stranded.

Unless indicated otherwise, the term “HDR” as used herein encompassesboth canonical HDR and alt-HDR.

“Non-homologous end joining” or “NHEJ” refers to ligation mediatedrepair and/or non-template mediated repair including canonical NHEJ(cNHEJ) and alternative NHEJ (altNHEJ), which in turn includesmicrohomology-mediated end joining (MMEJ), single-strand annealing(SSA), and synthesis-dependent microhomology-mediated end joining(SD-MMEJ).

“Replacement” or “replaced,” when used with reference to a modificationof a molecule (e.g. a nucleic acid or protein), does not require aprocess limitation but merely indicates that the replacement entity ispresent.

“Subject” means a human or non-human animal. A human subject can be anyage (e.g., an infant, child, young adult, or adult), and may suffer froma disease, or may be in need of alteration of a gene. Alternatively, thesubject may be an animal, which term includes, but is not limited to,mammals, birds, fish, reptiles, amphibians, and more particularlynon-human primates, rodents (such as mice, rats, hamsters, etc.),rabbits, guinea pigs, dogs, cats, and so on. In certain embodiments ofthis disclosure, the subject is livestock, e.g., a cow, a horse, asheep, or a goat. In certain embodiments, the subject is poultry.

“Treat,” “treating,” and “treatment” mean the treatment of a disease ina subject (e.g., a human subject), including one or more of inhibitingthe disease, i.e., arresting or preventing its development orprogression; relieving the disease, i.e., causing regression of thedisease state; relieving one or more symptoms of the disease; and curingthe disease.

“Prevent,” “preventing,” and “prevention” refer to the prevention of adisease in a mammal, e.g., in a human, including (a) avoiding orprecluding the disease; (b) affecting the predisposition toward thedisease; or (c) preventing or delaying the onset of at least one symptomof the disease.

A “Kit” refers to any collection of two or more components that togetherconstitute a functional unit that can be employed for a specificpurpose. By way of illustration (and not limitation), one kit accordingto this disclosure can include a guide RNA complexed or able to complexwith an RNA-guided nuclease, and accompanied by (e.g. suspended in, orsuspendable in) a pharmaceutically acceptable carrier. The kit can beused to introduce the complex into, for example, a cell or a subject,for the purpose of causing a desired genomic alteration in such cell orsubject. The components of a kit can be packaged together, or they maybe separately packaged. Kits according to this disclosure alsooptionally include directions for use (DFU) that describe the use of thekit e.g., according to a method of this disclosure. The DFU can bephysically packaged with the kit, or it can be made available to a userof the kit, for instance by electronic means.

The terms “polynucleotide”, “nucleotide sequence”, “nucleic acid”,“nucleic acid molecule”, “nucleic acid sequence”, and “oligonucleotide”refer to a series of nucleotide bases (also called “nucleotides”) in DNAand RNA, and mean any chain of two or more nucleotides. These termsrefer to compositions that can be chimeric mixtures or derivatives ormodified versions thereof, single-stranded or double-stranded. Theseterms also refer to compositions that can be modified at the basemoiety, sugar moiety, or phosphate backbone, for example, to improvestability of the molecule, its hybridization parameters, etc. Anucleotide sequence typically carries genetic information, including,but not limited to, the information used by cellular machinery to makeproteins and enzymes. These terms include double- or single-strandedgenomic DNA, RNA, any synthetic and genetically manipulatedpolynucleotide, and both sense and antisense polynucleotides. Theseterms also include nucleic acids containing modified bases.

Conventional IUPAC notation is used in nucleotide sequences presentedherein, as shown in Table 1, below (see also Cornish-Bowden A, NucleicAcids Res. 1985 May 10; 13(9):3021-30, incorporated by referenceherein). It should be noted, however, that “T” denotes “Thymine orUracil” in those instances where a sequence may be encoded by either DNAor RNA, for example in gRNA targeting domains.

TABLE 1 IUPAC nucleic acid notation Character Base A Adenine T Thymineor Uracil G Guanine C Cytosine U Uracil K G or T/U M A or C R A or G Y Cor T/U S C or G W A or T/U B C, G or T/U V A, C or G H A, C or T/U D A,G or T/U N A, C, G or T/U

The terms “protein,” “peptide” and “polypeptide” are usedinterchangeably to refer to a sequential chain of amino acids linkedtogether via peptide bonds. The terms include individual proteins,groups or complexes of proteins that associate together, as well asfragments or portions, variants, derivatives and analogs of suchproteins. Peptide sequences are presented herein using conventionalnotation, beginning with the amino or N-terminus on the left, andproceeding to the carboxyl or C-terminus on the right. Standardone-letter or three-letter abbreviations can be used.

Overview

In general terms, this disclosure concerns genome editing systems,including, but not limited to, transiently active genome editingsystems, comprising RNA-guided nucleases and gRNAs that are targeted tospecific, usually cellular, DNA sequences. The gRNAs used in thesegenome editing systems are referred to throughout this disclosure as“one-shot guide RNAs” or ogRNAs, to distinguish them from governingguide RNAs that are specifically targeted to nucleic acid sequencesencoding RNA-guided nucleases such as Cas9. In the various embodimentsof this disclosure, the nucleic acids encoding genome editing systemsare modified to introduce sites recognized by ogRNAs, allowing them tofunction as ggRNAs without altering their ability to recognize thespecific cellular sequences they have been designed to target. As such,in certain embodiments, the genome editing system can edit theendogenous target locus as well as the nucleic acid encoding theRNA-guided nuclease. FIG. 1A is a diagram illustrating a SaCas9-gRNAcomplex targeting the endogenous cellular locus as well as an engineeredCas9 sequence comprising an ogRNA target sequence in a viral vector.

For economy of presentation, and as illustrated in FIG. 1B, the sitesthat are introduced into nucleic acids encoding genome editing systemsare grouped into (a) sites introduced into nucleic acid vectorbackbones, e.g. viral genome backbones, and/or (b) sites introduced intoRNA-guided nuclease encoding sequences, for example, sequences encodinga Cas9 nuclease. This grouping is not intended to be limiting or bindingto any particular theory or model, and (a) and (b) are not mutuallyexclusive. The introduction of ogRNA target sites into sequencesencoding genome editing systems or vectors containing such sequences hasseveral advantages over other self-inactivation strategies. For onething, the introduction of an ogRNA target site into such nucleic acidsallows self-inactivating genome editing systems to be designed andimplemented without the need for a separate ggRNA. This in turn permitsself-inactivating genome editing systems to be packaged in comparativelyless space to facilitate, for example, a self-inactivating systemcomprising multiple gRNAs to be packaged in a single vector (a“one-shot” configuration) such as an AAV vector with a packaging limitof about 4.7 kb. Another advantage is a potential improvement in thepredictability of the behavior of the ogRNA relative to ggRNA systemsdue to, for example, the elimination of variation due to differences inexpression or cutting efficiency between a genomically-targeted gRNA anda ggRNA. Further advantages of the embodiments of this disclosure willbe evident to those of skill in the art. In certain embodiments, sitesintroduced into the RNA-guided nuclease do not alter the nucleaseactivity of the RNA-guided nuclease as compared to the wild-typeprotein. In certain embodiments, the engineered RNA guided-nuclease hasat least about 80%, about 85%, about 90%, about 95%, or about 99%nuclease activity of the wild-type protein.

Turning first to the introduction of engineered sequences into vectorbackbones, it will be understood by those of skill in the art that manyvector nucleic acids, such as plasmids, artificial chromosomes, and/orrecombinant viral vector genomes, comprise “backbone” sequences that donot encode RNA-guided nucleases. By engineering one or more ogRNA targetsites into these backbone sequences, the genome editing systemincorporating the ogRNA can recognize and alter the vector, for exampleby forming single- or double-strand breaks, point mutations, or othermodifications as described in greater detail below. This alteration, inturn, can reduce or eliminate transcription of one or more components ofthe genome editing system and thereby limit the activity of the genomeediting system.

An ogRNA target site, whether it is incorporated into a vector backboneor an RNA-guided nuclease coding sequence, will generally comprise a16-24 nucleotide sequence (a “protospacer” sequence) that iscomplementary to a targeting domain sequence (or “spacer”, 16-24nucleotide in length) of the ogRNA; the protospacer is adjacent to aProtospacer Adjacent Motif (or “PAM”) that is, generally, between 3 and6 nucleotides in length depending on the species of RNA-guided nucleaseused. Certain examples in this disclosure focus on target sites for usewith S. aureus Cas9, which recognizes an NNGRRT or NNGRRV PAM that isimmediately 3′ of the protospacer sequence as visualized on the “top” or“complementary” strand. Without limiting the foregoing, an exemplary S.aureus ogRNA target site can be 22-30 nucleotides in length, comprisinga 16-24 nucleic acid sequence in the eukaryotic gene and a 6 nucleotidePAM that is recognized by the S. aureus Cas9.

One-shot guide RNA target sites can be engineered into vector backbonesin any suitable position, though it may be advantageous in certain casesto position ogRNA target sites in proximity to sites or elements that(a) are required for the stability of the vector in vivo, (b) that willlose function, rather than gain function, when disrupted by, e.g. anindel; and/or (c) that are required for the expression of functionalRNA-guided nuclease. These sites or elements may include, withoutlimitation, promoter sequences for gRNAs and/or RNA-guided nucleases;inverted terminal repeats, gRNA coding sequences, etc.

In certain embodiments where the ogRNA target site is introduced into anucleic acid vector backbone, the target site is located within oradjacent to the promoter sequence of a gRNA and/or a RNA-guidednuclease. In certain embodiments, the target site is located upstream ofa transcription start site of the promoter sequence, e.g., 0 bp, about 1bp, about 10 bp, about 50 bp, about 100 bp, about 200 bp, about 500 bp,about 1000 bp, or any intermediate distance or ranges thereof upstreamof the transcription start site. In certain embodiments, the target siteis located downstream of a transcription start site of the promotersequence, e.g., 0 bp, about 1 bp, about 10 bp, about 50 bp, about 100bp, about 200 bp, about 500 bp, about 1000 bp, or any intermediatedistance or ranges thereof downstream of the transcription start site.In certain embodiments, the target site comprises a transcription startsite.

In certain embodiments where the ogRNA target site is introduced into anucleic acid vector backbone, the target site is located within oradjacent to a 5′ untranslated region (5′ UTR) of a RNA-guided nuclease.In certain embodiments, the target site is located upstream of atranslation start site of the promoter sequence, e.g., 0 bp, about 1 bp,about 10 bp, about 50 bp, about 100 bp, about 200 bp, about 500 bp,about 1000 bp, or any intermediate distance or ranges thereof upstreamof the translation start site. In certain embodiments, the target siteis located within or adjacent to a 3′ untranslated region (3′ UTR) of aRNA-guided nuclease. In certain embodiments, the target site is locateddownstream of a translation stop codon (e.g., TGA, TAA and TAG), e.g., 0bp, about 1 bp, about 10 bp, about 50 bp, about 100 bp, about 200 bp,about 500 bp, about 1000 bp, or any intermediate distance or rangesthereof downstream of the translation stop site.

Table 2, below, includes one exemplary AAV backbone into which a targetsite (denoted by N's) is engineered near the 5′ end (c.157insN₁₉₋₃₀)

TABLE 2 Exemplary in-backbone target sequenceTTGGCCACTCCCTCTCTGCGCGCTCGCTCGCTCACTGAGGCCGGGCGACCAAAGGTCGCCCGACGCCCGGGCTTTGCCCGGGCGGCCTCAGTGAGCGAGCGAGCGCGCAGAGAGGGAGTGGCCAACTCCATCACTAGGGGTTCCTCAGATCTGAATT NNNNNNNNNNNNNNNNNNNNNNNNNN CTAGCGCTTAAGTCGCGCATTGATTATTGACTAGTTATTAATAGTAATCAATTACGGGGTCATTAGTTCATAGCCCATATATGGAGTTCCGCGTTACATAACTTACGGTAAATGGCCCGCCTGGCTGACCGCCCAACGACCCCCGCCCATTGACGTCAATAATGACGTATGTTCCCATAGTAACGCCAATAGGGACTTTCCATTGACGTCAATGGGTGGACTATTTACGGTAAACTGCCCACTTGGCAGTACATCAAGTGTATCATATGCCAAGTACGCCCCCTATTGACGTCAATGACGGTAAATGGCCCGCCTGGCATTATGCCCAGTACATGACCTTATGGGACTTTCCTACTTGGCAGTACATCTACGTATTAGTCATCGCTATTACCATGGTGATGCGGTTTTGGCAGTACATCAATGGGCGTGGATAGCGGTTTGACTCACGGGGATTTCCAAGTCTCCACCCCATTGACGTCAATGGGAGTTTGTTTTGGCACCAAAATCAACGGGACTTTCCAAAATGTCGTAACAACTCCGCCCCATTGACGCAAATGGGCGGTAGGCGTGTACGGTGGGAGGTCTATATAAGCAGAGCTGGTTTAGTGAACCGTCAGATCCGCTAGAGATCCGCTCTAGAGGATCCGGTACTCGAGGAACTGAAAAACCAGAAAGTTAACTGGTAAGTTTAGTCTTTTTGTCTTTTATTTCAGGTCCCGGATCCGGTGGTGGTGCAAATCAAAGAACTGCTCCTCAGTGGATGTTGCCTTTACTTCTAGGCCTGTACGGAAGTGTTACGCGGCCGCCACCATGGGACCGAAGAAAAAGCGCAAGGTCGAAGCGTCCATGAAAAGGAACTACATTCTGGGGCTGGACATCGGGATTACAAGCGTGGGGTATGGGATTATTGACTATGAAACAAGGGACGTGATCGACGCAGGCGTCAGACTGTTCAAGGAGGCCAACGTGGAAAACAATGAGGGACGGAGAAGCAAGAGGGGAGCCAGGCGCCTGAAACGACGGAGAAGGCACAGAATCCAGAGGGTGAAGAAACTGCTGTTCGATTACAACCTGCTGACCGACCATTCTGAGCTGAGTGGAATTAATCCTTATGAAGCCAGGGTGAAAGGCCTGAGTCAGAAGCTGTCAGAGGAAGAGTTTTCCGCAGCTCTGCTGCACCTGGCTAAGCGCCGAGGAGTGCATAACGTCAATGAGGTGGAAGAGGACACCGGCAACGAGCTGTCTACAAAGGAACAGATCTCACGCAATAGCAAAGCTCTGGAAGAGAAGTATGTCGCAGAGCTGCAGCTGGAACGGCTGAAGAAAGATGGCGAGGTGAGAGGGTCAATTAATAGGTTCAAGACAAGCGACTACGTCAAAGAAGCCAAGCAGCTGCTGAAAGTGCAGAAGGCTTACCACCAGCTGGATCAGAGCTTCATCGATACTTATATCGACCTGCTGGAGACTCGGAGAACCTACTATGAGGGACCAGGAGAAGGGAGCCCCTTCGGATGGAAAGACATCAAGGAATGGTACGAGATGCTGATGGGACATTGCACCTATTTTCCAGAAGAGCTGAGAAGCGTCAAGTACGCTTATAACGCAGATCTGTACAACGCCCTGAATGACCTGAACAACCTGGTCATCACCAGGGATGAAAACGAGAAACTGGAATACTATGAGAAGTTCCAGATCATCGAAAACGTGTTTAAGCAGAAGAAAAAGCCTACACTGAAACAGATTGCTAAGGAGATCCTGGTCAACGAAGAGGACATCAAGGGCTACCGGGTGACAAGCACTGGAAAACCAGAGTTCACCAATCTGAAAGTGTATCACGATATTAAGGACATCACAGCACGGAAAGAAATCATTGAGAACGCCGAACTGCTGGATCAGATTGCTAAGATCCTGACTATCTACCAGAGCTCCGAGGACATCCAGGAAGAGCTGACTAACCTGAACAGCGAGCTGACCCAGGAAGAGATCGAACAGATTAGTAATCTGAAGGGGTACACCGGAACACACAACCTGTCCCTGAAAGCTATCAATCTGATTCTGGATGAGCTGTGGCATACAAACGACAATCAGATTGCAATCTTTAACCGGCTGAAGCTGGTCCCAAAAAAGGTGGACCTGAGTCAGCAGAAAGAGATCCCAACCACACTGGTGGACGATTTCATTCTGTCACCCGTGGTCAAGCGGAGCTTCATCCAGAGCATCAAAGTGATCAACGCCATCATCAAGAAGTACGGCCTGCCCAATGATATCATTATCGAGCTGGCTAGGGAGAAGAACAGCAAGGACGCACAGAAGATGATCAATGAGATGCAGAAACGAAACCGGCAGACCAATGAACGCATTGAAGAGATTATCCGAACTACCGGGAAAGAGAACGCAAAGTACCTGATTGAAAAAATCAAGCTGCACGATATGCAGGAGGGAAAGTGTCTGTATTCTCTGGAGGCCATCCCCCTGGAGGACCTGCTGAACAATCCATTCAACTACGAGGTCGATCATATTATCCCCAGAAGCGTGTCCTTCGACAATTCCTTTAACAACAAGGTGCTGGTCAAGCAGGAAGAGAACTCTAAAAAGGGCAATAGGACTCCTTTCCAGTACCTGTCTAGTTCAGATTCCAAGATCTCTTACGAAACCTTTAAAAAGCACATTCTGAATCTGGCCAAAGGAAAGGGCCGCATCAGCAAGACCAAAAAGGAGTACCTGCTGGAAGAGCGGGACATCAACAGATTCTCCGTCCAGAAGGATTTTATTAACCGGAATCTGGTGGACACAAGATACGCTACTCGCGGCCTGATGAATCTGCTGCGATCCTATTTCCGGGTGAACAATCTGGATGTGAAAGTCAAGTCCATCAACGGCGGGTTCACATCTTTTCTGAGGCGCAAATGGAAGTTTAAAAAGGAGCGCAACAAAGGGTACAAGCACCATGCCGAAGATGCTCTGATTATCGCAAATGCCGACTTCATCTTTAAGGAGTGGAAAAAGCTGGACAAAGCCAAGAAAGTGATGGAGAACCAGATGTTCGAAGAGAAGCAGGCCGAATCTATGCCCGAAATCGAGACAGAACAGGAGTACAAGGAGATTTTCATCACTCCTCACCAGATCAAGCATATCAAGGATTTCAAGGACTACAAGTACTCTCACCGGGTGGATAAAAAGCCCAACAGAGAGCTGATCAATGACACCCTGTATAGTACAAGAAAAGACGATAAGGGGAATACCCTGATTGTGAACAATCTGAACGGACTGTACGACAAAGATAATGACAAGCTGAAAAAGCTGATCAACAAAAGTCCCGAGAAGCTGCTGATGTACCACCATGATCCTCAGACATATCAGAAACTGAAGCTGATTATGGAGCAGTACGGCGACGAGAAGAACCCACTGTATAAGTACTATGAAGAGACTGGGAACTACCTGACCAAGTATAGCAAAAAGGATAATGGCCCCGTGATCAAGAAGATCAAGTACTATGGGAACAAGCTGAATGCCCATCTGGACATCACAGACGATTACCCTAACAGTCGCAACAAGGTGGTCAAGCTGTCACTGAAGCCATACAGATTCGATGTCTATCTGGACAACGGCGTGTATAAATTTGTGACTGTCAAGAATCTGGATGTCATCAAAAAGGAGAACTACTATGAAGTGAATAGCAAGTGCTACGAAGAGGCTAAAAAGCTGAAAAAGATTAGCAACCAGGCAGAGTTCATCGCCTCCTTTTACAACAACGACCTGATTAAGATCAATGGCGAACTGTATAGGGTCATCGGGGTGAACAATGATCTGCTGAACCGCATTGAAGTGAATATGATTGACATCACTTACCGAGAGTATCTGGAAAACATGAATGATAAGCGCCCCCCTCGAATTATCAAAACAATTGCCTCTAAGACTCAGAGTATCAAAAAGTACTCAACCGACATTCTGGGAAACCTGTATGAGGTGAAGAGCAAAAAGCACCCTCAGATTATCAAAAAGGGCGGATCCCCCAAGAAGAAGAGGAAAGTCTCGAGCGACTACAAAGACCATGACGGTGATTATAAAGATCATGACATCGATTACAAGGATGACGATGACAAGTAGCAATAAAGGATCGTTTATTTTCATTGGAAGCGTGTGTTGGTTTTTTGATCAGGCGCGTCCAAGCTTGCATGCTGGGGAGAGATCTAGGAACCCCTAGTGATGGAGTTGGCCACTCCCTCTCTGCGCGCTCGCTCGCTCACTGAGGCCGCCCGGGCAAAGCCCGGGCGTCGGGCGACCTTTGGTCGCCCGGCCTCAGTGAGCGAGCGAGCGCGCAGAGAGGGAGTGGCCAA [SEQ ID NO: 1]

While the exemplary backbone sequence of Table 2 includes a singletarget site, this disclosure also encompasses backbones into which 2, 3,4, 5 or more identical or non-identical target sequences are engineeredinto the vector. Additionally, it will be appreciated by those of skillin the art that certain sequences within the vector backbone may besimilar to portions of the target site, and that these sites may beeasily modified to create target sites. For example, there can bemultiple PAMs within the vector backbone, and the sequence immediately5′ (as visualized on the complementary or top strand) can be modified todiffer by 0, 1, 2, 3 or more nucleotides from the protospacer sequencerecognized by the ogRNA. Alternatively, a PAM sequence may be introducedinto a sequence encoding a gRNA targeting domain for example bymodifying the residues of the gRNA immediately 3′ of the targetingdomain. In certain embodiments, an isolated nucleic acid encoding a Cas9protein having a eukaryotic sequence can share at least 80% (e.g. 80%,85%, 90%, 95%, 96%, 97%, 98%, 99% or greater identity) sequence identitywith SEQ ID NO: 1. In certain embodiments, an isolated nucleic acidencoding a Cpf1 protein having a eukaryotic sequence can share at least80% (e.g. 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or greater identity)sequence identity with SEQ ID NO: 14.

Turning next to systems in which a target site is introduced into asequence encoding an RNA-guided nuclease, this disclosure providescertain engineered S. aureus Cas9 proteins that are encoded by DNAsequences comprising target sites as described above. Short (e.g. 24-42base pair, or 8-13 amino-acid) sequences comprising such target sitesare referred to as “inserts” when they are implemented in Cas9-codingsequences and/or engineered Cas9 proteins, whether they are insertedinto the sequence, or replace a portion of the sequence. FIGS. 3A-3C areschematic graphs showing exemplary peptide-encoding insertsincorporating heterologous cellular sequences.

Skilled artisans will appreciate that the design criteria for insertsinclude certain conditions that are not necessarily applicable to targetsites in the “backbone” sequence of a DNA vector. For one thing, thelength of the insert in certain embodiments is divisible by three toavoid the introduction of a frameshift mutation that may affect thefunction of the engineered RNA-guided nuclease. In instances wheregenomic target sites have a length that is not divisible by three, oneor two additional nucleotides are added to the insert as necessary topreserve the reading frame of the coding sequence comprising the insert.

Another design criterion that is met by certain embodiments of thisdisclosure is minimal disruption of the structure of the engineeredprotein comprising the insert. This requirement is met in some instancesby (a) locating the insert in a region of the nuclease protein where theaddition of amino acids is well tolerated, and/or (b) selecting insertsthat will tend not to disrupt the structure of the surrounding protein.These two design elements are dealt with in turn:

With respect to the location of the insert, FIGS. 1B and 2 depict fourexemplary sites (AC1, AC2, AC3, NT) in the S. aureus Cas9 protein intowhich an insert is added in various embodiments of this disclosure, e.g.E271_N272insGX₆₋₁₀(G, L371_N372insGX₆₋₁₀(G, Q737_A738insGX₆₋₁₀G, and/orat or near the N-terminus (NT). The peptide sequences corresponding toeach of these positions are presented in Table 3 below. In the table,residues within the insert are denoted by X. The sequences presentedinclude 10-12-amino acid inserts for clarity, however, the insert canhave any suitable length.

In certain embodiments, an insert “at or near the N-terminus” ispositioned within about 20 amino acid residues from the first amino acidresidue of an RNA-guided nuclease (e.g., Cas9 or Cpf1) peptide. Incertain embodiments, an insert at or near the N-terminus is positionedat about 0, about 1, about 2, about 3, about 4, about 5, about 6, about7, about 8, about 9, about 10, about 11, about 12, about 13, about 14,about 15, about 16, about 17, about 18, about 19, or about 20 amino acidresidues from the first amino acid residue of an RNA-guided nuclease(e.g., Cas9 or Cpf1) peptide. In certain embodiments, an insert at ornear the N-terminus is positioned upstream of the first amino acidresidue of an RNA-guided nuclease (e.g., Cas9 or Cpf1) peptide. Incertain embodiments, an insert at or near the N-terminus is positioneddownstream of the first amino acid residue of an RNA-guided nuclease(e.g., Cas9 or Cpf1) peptide. In certain embodiments, an insert at ornear the N-terminus is positioned between a nuclear localizationsequence (NLS) and the coding sequence for the RNA-guided nucleasepeptide. In certain embodiments, the NLS comprises a peptide sequenceset forth in SEQ ID NO: 12 GPKKKRKVEAS [SEQ ID NO: 12].

In certain embodiments, an insert at or near the N-terminus ispositioned within about 9 amino acid residues from the first amino acidresidue of a Cas9 peptide. In certain embodiments, an insert at or nearthe N-terminus is positioned at about 0, about 1, about 2, about 3,about 4, about 5, about 6, about 7, about 8, about 9 amino acid residuesfrom the first amino acid residue of a Cas9 peptide. In certainembodiments, an insert at or near the N-terminus is positioned withinabout 20 amino acid residues from the first amino acid residue of a Cpf1peptide. In certain embodiments, an insert at or near the N-terminus ispositioned at about 0, about 1, about 2, about 3, about 4, about 5,about 6, about 7, about 8, about 9, about 10, about 11, about 12, about13, about 14, about 15, about 16, about 17, about 18, about 19, or about20 amino acid residues from the first amino acid residue of a Cpf1peptide.

In certain embodiments, the insert can comprise a translational startcodon (i.e., ATG). In certain embodiments, the translational start codon(i.e., ATG) is in-frame with the RNA-guided nuclease coding sequence. Incertain embodiments, an insert at or near the N-terminus of theRNA-guided nuclease coding sequence is positioned between atranslational start codon (i.e., ATG) and the RNA-guided nuclease codingsequence.

Additionally, skilled artisans will appreciate that RNA-guided nucleasesequences (e.g., Cas9 or Cpf1 protein sequences) may be modified in waysthat do not disrupt the operation of the ogRNA, and that these sequencesmay be modified to have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more amino acidchanges. Said another way, in certain embodiments, sequences will havemore than 95% sequence identity to the corresponding naturally occurringRNA-guided nuclease. In certain embodiments, inserts added in thesethree exemplary sites do not alter the nuclease activity of theRNA-guided nuclease protein as compared to the wild-type RNA-guidednuclease. In certain embodiments, the RNA-guided nuclease with insertsadded in the exemplary sites will have at least about 40%, about 50%,about 60%, about 70%, about 80%, about 85%, about 90%, about 95%, orabout 99% nuclease activity of the wild-type RNA-guided nuclease.

TABLE 3 Exemplary engineered Cas9 proteins Sample S. aureus Cas9MKRNYILGLDIGITSVGYGIIDYETRDVIDAGVRLFKEANVENNEGRRSKRGARRLKRRRRHRIQRVKpeptide sequenceKLLFDYNLLTDHSELSGINPYEARVKGLSQKLSEEEFSAALLHLAKRRGVHNVNEVEEDIGNELSTKEQISRNSKALEEKYVAELQLERLKKDGEVRGSINRFKTSDYVKEAKQLLKVQKAYHQLDQSFIDTYIDLLETRRTYYEGPGEGSPFGWKDIKEWYEMLMGHCTYFPEELRSVKYAYNADLYNALNDLNNLVITRDENEKLEYYEKFQIIENVFKQKKKPTLKQIAKEILVNEEDIKGYRVTSTGKPEFTNLKVYHDIKDITARKEIIENAELLDQIAKILTIYQSSEDIQEELTNLNSELTQEEIEQISNLKGYTGTHNLSLKAINLILDELWHTNDNQIAIFNRLKLVPKKVDLSQQKEIPTTLVDDFILSPVVKRSFIQSIKVINAIIKKYGLPNDIIIELAREKNSKDAQKMINEMQKRNRQTNERIEEIIRTIGKENAKYLIEKIKLHDMQEGKCLYSLEAIPLEDLLNNPFNYEVDHIIPRSVSFDNSFNNKVLVKQEENSKKGNRTPFQYLSSSDSKISYETFKKHILNLAKGKGRISKTKKEYLLEERDINRFSVQKDFINRNLVDTRYATRGLMNLLRSYFRVNNLDVKVKSINGGFTSFLRRKWKFKKERNKGYKHHAEDALIIANADFIFKEWKKLDKAKKVMENQMFEEKQAESMPEIETEQEYKEIFITPHQIKHIKDFKDYKYSHRVDKKPNRELINDTLYSTRKDDKGNTLIVNNLNGLYDKDNDKLKKLINKSPEKLLMYHHDPQTYQKLKLIMEQYGDEKNPLYKYYEETGNYLTKYSKKDNGPVIKKIKYYGNKLNAHLDITDDYPNSRNKVVKLSLKPYRFDVYLDNGVYKFVTVKNLDVIKKENYYEVNSKCYEEAKKLKKISNQAEFIASFYNNDLIKINGELYRVIGVNNDLLNRIEVNMIDITYREYLENMNDKRPPRIIKTIASKTQSIKKYSTDILGNLYEVKSKKHPQIIKKG [SEQ ID NO: 2] Position 1MKRNYILGLDIGITSVGYGIIDYETRDVIDAGVRLFKEANVENNEGRRSKRGARRLKRRRRHRIQRVKE271_N272insGX₆₋₁₀GKLLFDYNLLTDHSELSGINPYEARVKGLSQKLSEEEFSAALLHLAKRRGVHNVNEVEEDTGNELSTKEQISRNSKALEEKYVAELQLERLKKDGEVRGSINRFKTSDYVKEAKQLLKVQKAYHQLDQSFIDTYIDLLETRRTYYEGPGEGSPFGWKDIKEWYEMLMGHCTYFPEELRSVKYAYNADLYNALNDLNNLVITRDE XXXXXXXXXXXX NEKLEYYEKFQIIENVFKQKKKPTLKQIAKEILVNEEDIKGYRVTSTGKPEFTNLKVYHDIKDITARKEIIENAELLDQIAKILTIYQSSEDIQEELTNLNSELTQEEIEQISNLKGYIGTHNLSLKAINLILDELWHTNDNQIAIFNRLKLVPKKVDLSQQKEIPTTLVDDFILSPVVKRSFIQSIKVINAIIKKYGLPNDIIIELAREKNSKDAQKMINEMQKRNRQTNERIEEIIRTTGKENAKYLIEKIKLHDMQEGKCLYSLEAIPLEDLLNNPFNYEVDHIIPRSVSFDNSFNNKVLVKQEENSKKGNRTPFQYLSSSDSKISYETFKKHILNLAKGKGRISKTKKEYLLEERDINRFSVQKDFINRNLVDTRYATRGLMNLLRSYFRVNNLDVKVKSINGGFTSFLRRKWKFKKERNKGYKHHAEDALIIANADFIFKEWKKLDKAKKVMENQMFEEKQAESMPEIETEQEYKEIFITPHQIKHIKDFKDYKYSHRVDKKPNRELINDTLYSTRKDDKGNTLIVNNLNGLYDKDNDKLKKLINKSPEKLLMYHHDPQTYQKLKLIMEQYGDEKNPLYKYYEETGNYLTKYSKKDNGPVIKKIKYYGNKLNAHLDITDDYPNSRNKVVKLSLKPYRFDVYLDNGVYKFVTVKNLDVIKKENYYEVNSKCYEEAKKLKKISNQAEFIASFYNNDLIKINGELYRVIGVNNDLLNRIEVNMIDITYREYLENMNDKRPPRIIKTIASKTQSIKKYSTDILGNLYEVKSKKHPQIIKKG [SEQ ID NO: 3] Position 2MKRNYILGLDIGITSVGYGIIDYETRDVIDAGVRLFKEANVENNEGRRSKRGARRLKRRRRHRIQRVKL371_N372insGX₆₋₁₀GKLLFDYNLLTDHSELSGINPYEARVKGLSQKLSEEEFSAALLHLAKRRGVHNVNEVEEDTGNELSTKEQISRNSKALEEKYVAELQLERLKKDGEVRGSINRFKTSDYVKEAKQLLKVQKAYHQLDQSFIDTYIDLLETRRTYYEGPGEGSPFGWKDIKEWYEMLMGHCTYFPEELRSVKYAYNADLYNALNDLNNLVITRDENEKLEYYEKFQIIENVFKQKKKPTLKQIAKEILVNEEDIKGYRVTSTGKPEFTNLKVYHDIKDITARKEIIENAELLDQIAKILTIYQSSEDIQEELTNL XXXXXXXXXXXX NSELTQEEIEQISNLKGYTGTHNLSLKAINLILDELWHTNDNQIAIFNRLKLVPKKVDLSQQKEIPTTLVDDFILSPVVKRSFIQSIKVINAIIKKYGLPNDIIIELAREKNSKDAQKMINEMQKRNRQTNERIEEIIRTTGKENAKYLIEKIKLHDMQEGKCLYSLEAIPLEDLLNNPFNYEVDHIIPRSVSFDNSFNNKVLVKQEENSKKGNRTPFQYLSSSDSKISYETFKKHILNLAKGKGRISKTKKEYLLEERDINRFSVQKDFINRNLVDTRYATRGLMNLLRSYFRVNNLDVKVKSINGGFTSFLRRKWKFKKERNKGYKHHAEDALIIANADFIFKEWKKLDKAKKVMENQMFEEKQAESMPEIETEQEYKEIFITPHQIKHIKDFKDYKYSHRVDKKPNRELINDTLYSTRKDDKGNTLIVNNLNGLYDKDNDKLKKLINKSPEKLLMYHHDPQTYQKLKLIMEQYGDEKNPLYKYYEETGNYLTKYSKKDNGPVIKKIKYYGNKLNAHLDITDDYPNSRNKVVKLSLKPYRFDVYLDNGVYKFVTVKNLDVIKKENYYEVNSKCYEEAKKLKKISNQAEFIASFYNNDLIKINGELYRVIGVNNDLLNRIEVNMIDITYREYLENMNDKRPPRIIKTIASKTQSIKKYSTDILGNLYEVKSKKHPQIIKKG [SEQ ID NO: 4] Position 3MKRNYILGLDIGITSVGYGIIDYETRDVIDAGVRLFKEANVENNEGRRSKRGARRLKRRRRHRIQRVKQ737_A738insGX₆₋₁₀GKLLFDYNLLTDHSELSGINPYEARVKGLSQKLSEEEFSAALLHLAKRRGVHNVNEVEEDTGNELSTKEQISRNSKALEEKYVAELQLERLKKDGEVRGSINRFKTSDYVKEAKQLLKVQKAYHQLDQSFIDTYIDLLETRRTYYEGPGEGSPFGWKDIKEWYEMLMGHCTYFPEELRSVKYAYNADLYNALNDLNNLVITRDENEKLEYYEKFQIIENVFKQKKKPTLKQIAKEILVNEEDIKGYRVTSTGKPEFTNLKVYHDIKDITARKEIIENAELLDQIAKILTIYQSSEDIQEELTNLNSELTQEEIEQISNLKGYTGTHNLSLKAINLILDELWHTNDNQIAIFNRLKLVPKKVDLSQQKEIPTTLVDDFILSPVVKRSFIQSIKVINAIIKKYGLPNDIIIELAREKNSKDAQKMINEMQKRNRQTNERIEEIIRTTGKENAKYLIEKIKLHDMQEGKCLYSLEAIPLEDLLNNPFNYEVDHIIPRSVSFDNSFNNKVLVKQEENSKKGNRTPFQYLSSSDSKISYETFKKHILNLAKGKGRISKTKKEYLLEERDINRFSVQKDFINRNLVDTRYATRGLMNLLRSYFRVNNLDVKVKSINGGFTSFLRRKWKFKKERNKGYKHHAEDALIIANADFIFKEWKKLDKAKKVMENQMFEEKQ XXXXXXXXXXX XAESMPEIETEQEYKEIFITPHQIKHIKDFKDYKYSHRVDKKPNRELINDTLYSTRKDDKGNTLIVNNLNGLYDKDNDKLKKLINKSPEKLLMYHHDPQTYQKLKLIMEQYGDEKNPLYKYYEETGNYLTKYSKKDNGPVIKKIKYYGNKLNAHLDITDDYPNSRNKVVKLSLKPYRFDVYLDNGVYKFVTVKNLDVIKKENYYEVNSKCYEEAKKLKKISNQAEFIASFYNNDLIKINGELYRVIGVNNDLLNRIEVNMIDITYREYLENMNDKRPPRIIKTIASKTQSIKKYSTDILGNLYEVKSKKHPQIIKKG [SEQ ID NO: 5] Position NTMGPKKKRKVEAS XXXXXXXXXXMKRNYILGLDIGITSVGYGIIDYETRDVIDAGVRLFKEANVENNEGRRSKRGARRLKRRRRHRIQRVKKLLFDYNLLTDHSELSGINPYEARVKGLSQKLSEEEFSAALLHLAKRRGVHNVNEVEEDTGNELSTKEQISRNSKALEEKYVAELQLERLKKDGEVRGSINRFKTSDYVKEAKQLLKVQKAYHQLDQSFIDTYIDLLETRRTYYEGPGEGSPFGWKDIKEWYEMLMGHCTYFPEELRSVKYAYNADLYNALNDLNNLVITRDENEKLEYYEKFQIIENVFKQKKKPTLKQIAKEILVNEEDIKGYRVTSTGKPEFTNLKVYHDIKDITARKEIIENAELLDQIAKILTIYQSSEDIQEELTNLNSELTQEEIEQISNLKGYTGTHNLSLKAINLILDELWHTNDNQIAIFNRLKLVPKKVDLSQQKEIPTTLVDDFILSPVVKRSFIQSIKVINAIIKKYGLPNDIIIELAREKNSKDAQKMINEMQKRNRQTNERIEEIIRTTGKENAKYLIEKIKLHDMQEGKCLYSLEAIPLEDLLNNPFNYEVDHIIPRSVSFDNSFNNKVLVKQEENSKKGNRTPFQYLSSSDSKISYETFKKHILNLAKGKGRISKTKKEYLLEERDINRFSVQKDFINRNLVDTRYATRGLMNLLRSYFRVNNLDVKVKSINGGFTSFLRRKWKFKKERNKGYKHHAEDALIIANADFIFKEWKKLDKAKKVMENQMFEEKQAESMPEIETEQEYKEIFITPHQIKHIKDFKDYKYSHRVDKKPNRELINDTLYSTRKDDKGNTLIVNNLNGLYDKDNDKLKKLINKSPEKLLMYHHDPQTYQKLKLIMEQYGDEKNPLYKYYEETGNYLTKYSKKDNGPVIKKIKYYGNKLNAHLDITDDYPNSRNKVVKLSLKPYRFDVYLDNGVYKFVTVKNLDVIKKENYYEVNSKCYEEAKKLKKISNQAEFIASFYNNDLIKINGELYRVIGVNNDLLNRIEVNMIDITYREYLENMNDKRPPRIIKTIASKTQSIKKYSTDILGNLYEVKSKKHPQIIKKG [SEQ ID NO: 10]

The engineered Cas9 proteins presented in Table 3 are encoded by theexemplary nucleic acids sequences listed in Table 4. In the table, thenucleotides within the insert are denoted by N, and insert positionscorresponding to amino acid positions 1-3 are c.813_814insN₂₇₋₃₆,c.1113_1114insN₂₇₋₃₆, and c.2211_2212insN₂₇₋₃₆, respectively.

TABLE 4Exemplary nucleic acid sequences encoding engineered Cas9 proteinsSample codon-optimizedATGAAAAGGAACTACATTCTGGGGCTGGACATCGGGATTACAAGCGTGGGGTATGGGATTATTGACTAS. aureus Cas9 sequenceTGAAACAAGGGACGTGATCGACGCAGGCGTCAGACTGTTCAAGGAGGCCAACGTGGAAAACAATGAGGGACGGAGAAGCAAGAGGGGAGCCAGGCGCCTGAAACGACGGAGAAGGCACAGAATCCAGAGGGTGAAGAAACTGCTGTTCGATTACAACCTGCTGACCGACCATTCTGAGCTGAGTGGAATTAATCCTTATGAAGCCAGGGTGAAAGGCCTGAGTCAGAAGCTGTCAGAGGAAGAGTTTTCCGCAGCTCTGCTGCACCTGGCTAAGCGCCGAGGAGTGCATAACGTCAATGAGGTGGAAGAGGACACCGGCAACGAGCTGTCTACAAAGGAACAGATCTCACGCAATAGCAAAGCTCTGGAAGAGAAGTATGTCGCAGAGCTGCAGCTGGAACGGCTGAAGAAAGATGGCGAGGTGAGAGGGTCAATTAATAGGTTCAAGACAAGCGACTACGTCAAAGAAGCCAAGCAGCTGCTGAAAGTGCAGAAGGCTTACCACCAGCTGGATCAGAGCTTCATCGATACTTATATCGACCTGCTGGAGACTCGGAGAACCTACTATGAGGGACCAGGAGAAGGGAGCCCCTTCGGATGGAAAGACATCAAGGAATGGTACGAGATGCTGATGGGACATTGCACCTATTTTCCAGAAGAGCTGAGAAGCGTCAAGTACGCTTATAACGCAGATCTGTACAACGCCCTGAATGACCTGAACAACCTGGTCATCACCAGGGATGAAAACGAGAAACTGGAATACTATGAGAAGTTCCAGATCATCGAAAACGTGTTTAAGCAGAAGAAAAAGCCTACACTGAAACAGATTGCTAAGGAGATCCTGGTCAACGAAGAGGACATCAAGGGCTACCGGGTGACAAGCACTGGAAAACCAGAGTTCACCAATCTGAAAGTGTATCACGATATTAAGGACATCACAGCACGGAAAGAAATCATTGAGAACGCCGAACTGCTGGATCAGATTGCTAAGATCCTGACTATCTACCAGAGCTCCGAGGACATCCAGGAAGAGCTGACTAACCTGAACAGCGAGCTGACCCAGGAAGAGATCGAACAGATTAGTAATCTGAAGGGGTACACCGGAACACACAACCTGTCCCTGAAAGCTATCAATCTGATTCTGGATGAGCTGTGGCATACAAACGACAATCAGATTGCAATCTTTAACCGGCTGAAGCTGGTCCCAAAAAAGGTGGACCTGAGTCAGCAGAAAGAGATCCCAACCACACTGGTGGACGATTTCATTCTGTCACCCGTGGTCAAGCGGAGCTTCATCCAGAGCATCAAAGTGATCAACGCCATCATCAAGAAGTACGGCCTGCCCAATGATATCATTATCGAGCTGGCTAGGGAGAAGAACAGCAAGGACGCACAGAAGATGATCAATGAGATGCAGAAACGAAACCGGCAGACCAATGAACGCATTGAAGAGATTATCCGAACTACCGGGAAAGAGAACGCAAAGTACCTGATTGAAAAAATCAAGCTGCACGATATGCAGGAGGGAAAGTGTCTGTATTCTCTGGAGGCCATCCCCCTGGAGGACCTGCTGAACAATCCATTCAACTACGAGGTCGATCATATTATCCCCAGAAGCGTGTCCTTCGACAATTCCTTTAACAACAAGGTGCTGGTCAAGCAGGAAGAGAACTCTAAAAAGGGCAATAGGACTCCTTTCCAGTACCTGTCTAGTTCAGATTCCAAGATCTCTTACGAAACCTTTAAAAAGCACATTCTGAATCTGGCCAAAGGAAAGGGCCGCATCAGCAAGACCAAAAAGGAGTACCTGCTGGAAGAGCGGGACATCAACAGATTCTCCGTCCAGAAGGATTTTATTAACCGGAATCTGGTGGACACAAGATACGCTACTCGCGGCCTGATGAATCTGCTGCGATCCTATTTCCGGGTGAACAATCTGGATGTGAAAGTCAAGTCCATCAACGGCGGGTTCACATCTTTTCTGAGGCGCAAATGGAAGTTTAAAAAGGAGCGCAACAAAGGGTACAAGCACCATGCCGAAGATGCTCTGATTATCGCAAATGCCGACTTCATCTTTAAGGAGTGGAAAAAGCTGGACAAAGCCAAGAAAGTGATGGAGAACCAGATGTTCGAAGAGAAGCAGGCCGAATCTATGCCCGAAATCGAGACAGAACAGGAGTACAAGGAGATTTTCATCACTCCTCACCAGATCAAGCATATCAAGGATTTCAAGGACTACAAGTACTCTCACCGGGTGGATAAAAAGCCCAACAGAGAGCTGATCAATGACACCCTGTATAGTACAAGAAAAGACGATAAGGGGAATACCCTGATTGTGAACAATCTGAACGGACTGTACGACAAAGATAATGACAAGCTGAAAAAGCTGATCAACAAAAGTCCCGAGAAGCTGCTGATGTACCACCATGATCCTCAGACATATCAGAAACTGAAGCTGATTATGGAGCAGTACGGCGACGAGAAGAACCCACTGTATAAGTACTATGAAGAGACTGGGAACTACCTGACCAAGTATAGCAAAAAGGATAATGGCCCCGTGATCAAGAAGATCAAGTACTATGGGAACAAGCTGAATGCCCATCTGGACATCACAGACGATTACCCTAACAGTCGCAACAAGGTGGTCAAGCTGTCACTGAAGCCATACAGATTCGATGTCTATCTGGACAACGGCGTGTATAAATTTGTGACTGTCAAGAATCTGGATGTCATCAAAAAGGAGAACTACTATGAAGTGAATAGCAAGTGCTACGAAGAGGCTAAAAAGCTGAAAAAGATTAGCAACCAGGCAGAGTTCATCGCCTCCTTTTACAACAACGACCTGATTAAGATCAATGGCGAACTGTATAGGGTCATCGGGGTGAACAATGATCTGCTGAACCGCATTGAAGTGAATATGATTGACATCACTTACCGAGAGTATCTGGAAAACATGAATGATAAGCGCCCCCCTCGAATTATCAAAACAATTGCCTCTAAGACTCAGAGTATCAAAAAGTACTCAACCGACATTCTGGGAAACCTGTATGAGGTGAAGAGCAAAAAGCACCCTCAGATTATCAAAAAGGGC [SEQ ID NO: 6] Position 1ATGAAAAGGAACTACATTCTGGGGCTGGACATCGGGATTACAAGCGTGGGGTATGGGATTATTGACTAc.813_814insN₂₇₋₃₆TGAAACAAGGGACGTGATCGACGCAGGCGTCAGACTGTTCAAGGAGGCCAACGTGGAAAACAATGAGGGACGGAGAAGCAAGAGGGGAGCCAGGCGCCTGAAACGACGGAGAAGGCACAGAATCCAGAGGGTGAAGAAACTGCTGTTCGATTACAACCTGCTGACCGACCATTCTGAGCTGAGTGGAATTAATCCTTATGAAGCCAGGGTGAAAGGCCTGAGTCAGAAGCTGTCAGAGGAAGAGTTTTCCGCAGCTCTGCTGCACCTGGCTAAGCGCCGAGGAGTGCATAACGTCAATGAGGTGGAAGAGGACACCGGCAACGAGCTGTCTACAAAGGAACAGATCTCACGCAATAGCAAAGCTCTGGAAGAGAAGTATGTCGCAGAGCTGCAGCTGGAACGGCTGAAGAAAGATGGCGAGGTGAGAGGGTCAATTAATAGGTTCAAGACAAGCGACTACGTCAAAGAAGCCAAGCAGCTGCTGAAAGTGCAGAAGGCTTACCACCAGCTGGATCAGAGCTTCATCGATACTTATATCGACCTGCTGGAGACTCGGAGAACCTACTATGAGGGACCAGGAGAAGGGAGCCCCTTCGGATGGAAAGACATCAAGGAATGGTACGAGATGCTGATGGGACATTGCACCTATTTTCCAGAAGAGCTGAGAAGCGTCAAGTACGCTTATAACGCAGATCTGTACAACGCCCTGAATGACCTGAACAACCTGGTCATCACCAGGGATGAA NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN AACGAGAAACTGGAATACTATGAGAAGTTCCAGATCATCGAAAACGTGTTTAAGCAGAAGAAAAAGCCTACACTGAAACAGATTGCTAAGGAGATCCTGGTCAACGAAGAGGACATCAAGGGCTACCGGGTGACAAGCACTGGAAAACCAGAGTTCACCAATCTGAAAGTGTATCACGATATTAAGGACATCACAGCACGGAAAGAAATCATTGAGAACGCCGAACTGCTGGATCAGATTGCTAAGATCCTGACTATCTACCAGAGCTCCGAGGACATCCAGGAAGAGCTGACTAACCTGAACAGCGAGCTGACCCAGGAAGAGATCGAACAGATTAGTAATCTGAAGGGGTACACCGGAACACACAACCTGTCCCTGAAAGCTATCAATCTGATTCTGGATGAGCTGTGGCATACAAACGACAATCAGATTGCAATCTTTAACCGGCTGAAGCTGGTCCCAAAAAAGGTGGACCTGAGTCAGCAGAAAGAGATCCCAACCACACTGGTGGACGATTTCATTCTGTCACCCGTGGTCAAGCGGAGCTTCATCCAGAGCATCAAAGTGATCAACGCCATCATCAAGAAGTACGGCCTGCCCAATGATATCATTATCGAGCTGGCTAGGGAGAAGAACAGCAAGGACGCACAGAAGATGATCAATGAGATGCAGAAACGAAACCGGCAGACCAATGAACGCATTGAAGAGATTATCCGAACTACCGGGAAAGAGAACGCAAAGTACCTGATTGAAAAAATCAAGCTGCACGATATGCAGGAGGGAAAGTGTCTGTATTCTCTGGAGGCCATCCCCCTGGAGGACCTGCTGAACAATCCATTCAACTACGAGGTCGATCATATTATCCCCAGAAGCGTGTCCTTCGACAATTCCTTTAACAACAAGGTGCTGGTCAAGCAGGAAGAGAACTCTAAAAAGGGCAATAGGACTCCTTTCCAGTACCTGTCTAGTTCAGATTCCAAGATCTCTTACGAAACCTTTAAAAAGCACATTCTGAATCTGGCCAAAGGAAAGGGCCGCATCAGCAAGACCAAAAAGGAGTACCTGCTGGAAGAGCGGGACATCAACAGATTCTCCGTCCAGAAGGATTTTATTAACCGGAATCTGGTGGACACAAGATACGCTACTCGCGGCCTGATGAATCTGCTGCGATCCTATTTCCGGGTGAACAATCTGGATGTGAAAGTCAAGTCCATCAACGGCGGGTTCACATCTTTTCTGAGGCGCAAATGGAAGTTTAAAAAGGAGCGCAACAAAGGGTACAAGCACCATGCCGAAGATGCTCTGATTATCGCAAATGCCGACTTCATCTTTAAGGAGTGGAAAAAGCTGGACAAAGCCAAGAAAGTGATGGAGAACCAGATGTTCGAAGAGAAGCAGGCCGAATCTATGCCCGAAATCGAGACAGAACAGGAGTACAAGGAGATTTTCATCACTCCTCACCAGATCAAGCATATCAAGGATTTCAAGGACTACAAGTACTCTCACCGGGTGGATAAAAAGCCCAACAGAGAGCTGATCAATGACACCCTGTATAGTACAAGAAAAGACGATAAGGGGAATACCCTGATTGTGAACAATCTGAACGGACTGTACGACAAAGATAATGACAAGCTGAAAAAGCTGATCAACAAAAGTCCCGAGAAGCTGCTGATGTACCACCATGATCCTCAGACATATCAGAAACTGAAGCTGATTATGGAGCAGTACGGCGACGAGAAGAACCCACTGTATAAGTACTATGAAGAGACTGGGAACTACCTGACCAAGTATAGCAAAAAGGATAATGGCCCCGTGATCAAGAAGATCAAGTACTATGGGAACAAGCTGAATGCCCATCTGGACATCACAGACGATTACCCTAACAGTCGCAACAAGGTGGTCAAGCTGTCACTGAAGCCATACAGATTCGATGTCTATCTGGACAACGGCGTGTATAAATTTGTGACTGTCAAGAATCTGGATGTCATCAAAAAGGAGAACTACTATGAAGTGAATAGCAAGTGCTACGAAGAGGCTAAAAAGCTGAAAAAGATTAGCAACCAGGCAGAGTTCATCGCCTCCTTTTACAACAACGACCTGATTAAGATCAATGGCGAACTGTATAGGGTCATCGGGGTGAACAATGATCTGCTGAACCGCATTGAAGTGAATATGATTGACATCACTTACCGAGAGTATCTGGAAAACATGAATGATAAGCGCCCCCCTCGAATTATCAAAACAATTGCCTCTAAGACTCAGAGTATCAAAAAGTACTCAACCGACATTCTGGGAAACCTGTATGAGGTGAAGAGCAAAAAGCACCCTCAGATTATCAAAAAGGGC[SEQ ID NO: 7] Position 2ATGAAAAGGAACTACATTCTGGGGCTGGACATCGGGATTACAAGCGTGGGGTATGGGATTATTGACTAc.1113_1114insN₂₇₋₃₆TGAAACAAGGGACGTGATCGACGCAGGCGTCAGACTGTTCAAGGAGGCCAACGTGGAAAACAATGAGGGACGGAGAAGCAAGAGGGGAGCCAGGCGCCTGAAACGACGGAGAAGGCACAGAATCCAGAGGGTGAAGAAACTGCTGTTCGATTACAACCTGCTGACCGACCATTCTGAGCTGAGTGGAATTAATCCTTATGAAGCCAGGGTGAAAGGCCTGAGTCAGAAGCTGTCAGAGGAAGAGTTTTCCGCAGCTCTGCTGCACCTGGCTAAGCGCCGAGGAGTGCATAACGTCAATGAGGTGGAAGAGGACACCGGCAACGAGCTGTCTACAAAGGAACAGATCTCACGCAATAGCAAAGCTCTGGAAGAGAAGTATGTCGCAGAGCTGCAGCTGGAACGGCTGAAGAAAGATGGCGAGGTGAGAGGGTCAATTAATAGGTTCAAGACAAGCGACTACGTCAAAGAAGCCAAGCAGCTGCTGAAAGTGCAGAAGGCTTACCACCAGCTGGATCAGAGCTTCATCGATACTTATATCGACCTGCTGGAGACTCGGAGAACCTACTATGAGGGACCAGGAGAAGGGAGCCCCTTCGGATGGAAAGACATCAAGGAATGGTACGAGATGCTGATGGGACATTGCACCTATTTTCCAGAAGAGCTGAGAAGCGTCAAGTACGCTTATAACGCAGATCTGTACAACGCCCTGAATGACCTGAACAACCTGGTCATCACCAGGGATGAAAACGAGAAACTGGAATACTATGAGAAGTTCCAGATCATCGAAAACGTGTTTAAGCAGAAGAAAAAGCCTACACTGAAACAGATTGCTAAGGAGATCCTGGTCAACGAAGAGGACATCAAGGGCTACCGGGTGACAAGCACTGGAAAACCAGAGTTCACCAATCTGAAAGTGTATCACGATATTAAGGACATCACAGCACGGAAAGAAATCATTGAGAACGCCGAACTGCTGGATCAGATTGCTAAGATCCTGACTATCTACCAGAGCTCCGAGGACATCCAGGAAGAGCTGACTAACCTG NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN AACAGCGAGCTGACCCAGGAAGAGATCGAACAGATTAGTAATCTGAAGGGGTACACCGGAACACACAACCTGTCCCTGAAAGCTATCAATCTGATTCTGGATGAGCTGTGGCATACAAACGACAATCAGATTGCAATCTTTAACCGGCTGAAGCTGGTCCCAAAAAAGGTGGACCTGAGTCAGCAGAAAGAGATCCCAACCACACTGGTGGACGATTTCATTCTGTCACCCGTGGTCAAGCGGAGCTTCATCCAGAGCATCAAAGTGATCAACGCCATCATCAAGAAGTACGGCCTGCCCAATGATATCATTATCGAGCTGGCTAGGGAGAAGAACAGCAAGGACGCACAGAAGATGATCAATGAGATGCAGAAACGAAACCGGCAGACCAATGAACGCATTGAAGAGATTATCCGAACTACCGGGAAAGAGAACGCAAAGTACCTGATTGAAAAAATCAAGCTGCACGATATGCAGGAGGGAAAGTGTCTGTATTCTCTGGAGGCCATCCCCCTGGAGGACCTGCTGAACAATCCATTCAACTACGAGGTCGATCATATTATCCCCAGAAGCGTGTCCTTCGACAATTCCTTTAACAACAAGGTGCTGGTCAAGCAGGAAGAGAACTCTAAAAAGGGCAATAGGACTCCTTTCCAGTACCTGTCTAGTTCAGATTCCAAGATCTCTTACGAAACCTTTAAAAAGCACATTCTGAATCTGGCCAAAGGAAAGGGCCGCATCAGCAAGACCAAAAAGGAGTACCTGCTGGAAGAGCGGGACATCAACAGATTCTCCGTCCAGAAGGATTTTATTAACCGGAATCTGGTGGACACAAGATACGCTACTCGCGGCCTGATGAATCTGCTGCGATCCTATTTCCGGGTGAACAATCTGGATGTGAAAGTCAAGTCCATCAACGGCGGGTTCACATCTTTTCTGAGGCGCAAATGGAAGTTTAAAAAGGAGCGCAACAAAGGGTACAAGCACCATGCCGAAGATGCTCTGATTATCGCAAATGCCGACTTCATCTTTAAGGAGTGGAAAAAGCTGGACAAAGCCAAGAAAGTGATGGAGAACCAGATGTTCGAAGAGAAGCAGGCCGAATCTATGCCCGAAATCGAGACAGAACAGGAGTACAAGGAGATTTTCATCACTCCTCACCAGATCAAGCATATCAAGGATTTCAAGGACTACAAGTACTCTCACCGGGTGGATAAAAAGCCCAACAGAGAGCTGATCAATGACACCCTGTATAGTACAAGAAAAGACGATAAGGGGAATACCCTGATTGTGAACAATCTGAACGGACTGTACGACAAAGATAATGACAAGCTGAAAAAGCTGATCAACAAAAGTCCCGAGAAGCTGCTGATGTACCACCATGATCCTCAGACATATCAGAAACTGAAGCTGATTATGGAGCAGTACGGCGACGAGAAGAACCCACTGTATAAGTACTATGAAGAGACTGGGAACTACCTGACCAAGTATAGCAAAAAGGATAATGGCCCCGTGATCAAGAAGATCAAGTACTATGGGAACAAGCTGAATGCCCATCTGGACATCACAGACGATTACCCTAACAGTCGCAACAAGGTGGTCAAGCTGTCACTGAAGCCATACAGATTCGATGTCTATCTGGACAACGGCGTGTATAAATTTGTGACTGTCAAGAATCTGGATGTCATCAAAAAGGAGAACTACTATGAAGTGAATAGCAAGTGCTACGAAGAGGCTAAAAAGCTGAAAAAGATTAGCAACCAGGCAGAGTTCATCGCCTCCTTTTACAACAACGACCTGATTAAGATCAATGGCGAACTGTATAGGGTCATCGGGGTGAACAATGATCTGCTGAACCGCATTGAAGTGAATATGATTGACATCACTTACCGAGAGTATCTGGAAAACATGAATGATAAGCGCCCCCCTCGAATTATCAAAACAATTGCCTCTAAGACTCAGAGTATCAAAAAGTACTCAACCGACATTCTGGGAAACCTGTATGAGGTGAAGAGCAAAAAGCACCCTCAGATTATCAAAAAGGGC[SEQ ID NO: 8] Position 3ATGAAAAGGAACTACATTCTGGGGCTGGACATCGGGATTACAAGCGTGGGGTATGGGATTATTGACTAc.2211_2212insN₂₇₋₃₆TGAAACAAGGGACGTGATCGACGCAGGCGTCAGACTGTTCAAGGAGGCCAACGTGGAAAACAATGAGGGACGGAGAAGCAAGAGGGGAGCCAGGCGCCTGAAACGACGGAGAAGGCACAGAATCCAGAGGGTGAAGAAACTGCTGTTCGATTACAACCTGCTGACCGACCATTCTGAGCTGAGTGGAATTAATCCTTATGAAGCCAGGGTGAAAGGCCTGAGTCAGAAGCTGTCAGAGGAAGAGTTTTCCGCAGCTCTGCTGCACCTGGCTAAGCGCCGAGGAGTGCATAACGTCAATGAGGTGGAAGAGGACACCGGCAACGAGCTGTCTACAAAGGAACAGATCTCACGCAATAGCAAAGCTCTGGAAGAGAAGTATGTCGCAGAGCTGCAGCTGGAACGGCTGAAGAAAGATGGCGAGGTGAGAGGGTCAATTAATAGGTTCAAGACAAGCGACTACGTCAAAGAAGCCAAGCAGCTGCTGAAAGTGCAGAAGGCTTACCACCAGCTGGATCAGAGCTTCATCGATACTTATATCGACCTGCTGGAGACTCGGAGAACCTACTATGAGGGACCAGGAGAAGGGAGCCCCTTCGGATGGAAAGACATCAAGGAATGGTACGAGATGCTGATGGGACATTGCACCTATTTTCCAGAAGAGCTGAGAAGCGTCAAGTACGCTTATAACGCAGATCTGTACAACGCCCTGAATGACCTGAACAACCTGGTCATCACCAGGGATGAAAACGAGAAACTGGAATACTATGAGAAGTTCCAGATCATCGAAAACGTGTTTAAGCAGAAGAAAAAGCCTACACTGAAACAGATTGCTAAGGAGATCCTGGTCAACGAAGAGGACATCAAGGGCTACCGGGTGACAAGCACTGGAAAACCAGAGTTCACCAATCTGAAAGTGTATCACGATATTAAGGACATCACAGCACGGAAAGAAATCATTGAGAACGCCGAACTGCTGGATCAGATTGCTAAGATCCTGACTATCTACCAGAGCTCCGAGGACATCCAGGAAGAGCTGACTAACCTGAACAGCGAGCTGACCCAGGAAGAGATCGAACAGATTAGTAATCTGAAGGGGTACACCGGAACACACAACCTGTCCCTGAAAGCTATCAATCTGATTCTGGATGAGCTGTGGCATACAAACGACAATCAGATTGCAATCTTTAACCGGCTGAAGCTGGTCCCAAAAAAGGTGGACCTGAGTCAGCAGAAAGAGATCCCAACCACACTGGTGGACGATTTCATTCTGTCACCCGTGGTCAAGCGGAGCTTCATCCAGAGCATCAAAGTGATCAACGCCATCATCAAGAAGTACGGCCTGCCCAATGATATCATTATCGAGCTGGCTAGGGAGAAGAACAGCAAGGACGCACAGAAGATGATCAATGAGATGCAGAAACGAAACCGGCAGACCAATGAACGCATTGAAGAGATTATCCGAACTACCGGGAAAGAGAACGCAAAGTACCTGATTGAAAAAATCAAGCTGCACGATATGCAGGAGGGAAAGTGTCTGTATTCTCTGGAGGCCATCCCCCTGGAGGACCTGCTGAACAATCCATTCAACTACGAGGTCGATCATATTATCCCCAGAAGCGTGTCCTTCGACAATTCCTTTAACAACAAGGTGCTGGTCAAGCAGGAAGAGAACTCTAAAAAGGGCAATAGGACTCCTTTCCAGTACCTGTCTAGTTCAGATTCCAAGATCTCTTACGAAACCTTTAAAAAGCACATTCTGAATCTGGCCAAAGGAAAGGGCCGCATCAGCAAGACCAAAAAGGAGTACCTGCTGGAAGAGCGGGACATCAACAGATTCTCCGTCCAGAAGGATTTTATTAACCGGAATCTGGTGGACACAAGATACGCTACTCGCGGCCTGATGAATCTGCTGCGATCCTATTTCCGGGTGAACAATCTGGATGTGAAAGTCAAGTCCATCAACGGCGGGTTCACATCTTTTCTGAGGCGCAAATGGAAGTTTAAAAAGGAGCGCAACAAAGGGTACAAGCACCATGCCGAAGATGCTCTGATTATCGCAAATGCCGACTTCATCTTTAAGGAGTGGAAAAAGCTGGACAAAGCCAAGAAAGTGATGGAGAACCAGATGTTCGAAGAGAAGCAG NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN GCCGAATCTATGCCCGAAATCGAGACAGAACAGGAGTACAAGGAGATTTTCATCACTCCTCACCAGATCAAGCATATCAAGGATTTCAAGGACTACAAGTACTCTCACCGGGTGGATAAAAAGCCCAACAGAGAGCTGATCAATGACACCCTGTATAGTACAAGAAAAGACGATAAGGGGAATACCCTGATTGTGAACAATCTGAACGGACTGTACGACAAAGATAATGACAAGCTGAAAAAGCTGATCAACAAAAGTCCCGAGAAGCTGCTGATGTACCACCATGATCCTCAGACATATCAGAAACTGAAGCTGATTATGGAGCAGTACGGCGACGAGAAGAACCCACTGTATAAGTACTATGAAGAGACTGGGAACTACCTGACCAAGTATAGCAAAAAGGATAATGGCCCCGTGATCAAGAAGATCAAGTACTATGGGAACAAGCTGAATGCCCATCTGGACATCACAGACGATTACCCTAACAGTCGCAACAAGGTGGTCAAGCTGTCACTGAAGCCATACAGATTCGATGTCTATCTGGACAACGGCGTGTATAAATTTGTGACTGTCAAGAATCTGGATGTCATCAAAAAGGAGAACTACTATGAAGTGAATAGCAAGTGCTACGAAGAGGCTAAAAAGCTGAAAAAGATTAGCAACCAGGCAGAGTTCATCGCCTCCTTTTACAACAACGACCTGATTAAGATCAATGGCGAACTGTATAGGGTCATCGGGGTGAACAATGATCTGCTGAACCGCATTGAAGTGAATATGATTGACATCACTTACCGAGAGTATCTGGAAAACATGAATGATAAGCGCCCCCCTCGAATTATCAAAACAATTGCCTCTAAGACTCAGAGTATCAAAAAGTACTCAACCGACATTCTGGGAAACCTGTATGAGGTGAAGAGCAAAAAGCACCCTCAGATTATCAAAAAGGGC[SEQ ID NO: 9] Position NT ATGGGACCGAAGAAAAAGCGCAAGGTCGAAGCGTCCNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN ATGAAAAGGAACTACATTCTGGGGCTGGACATCGGGATTACAAGCGTGGGGTATGGGATTATTGACTATGAAACAAGGGACGTGATCGACGCAGGCGTCAGACTGTTCAAGGAGGCCAACGTGGAAAACAATGAGGGACGGAGAAGCAAGAGGGGAGCCAGGCGCCTGAAACGACGGAGAAGGCACAGAATCCAGAGGGTGAAGAAACTGCTGTTCGATTACAACCTGCTGACCGACCATTCTGAGCTGAGTGGAATTAATCCTTATGAAGCCAGGGTGAAAGGCCTGAGTCAGAAGCTGTCAGAGGAAGAGTTTTCCGCAGCTCTGCTGCACCTGGCTAAGCGCCGAGGAGTGCATAACGTCAATGAGGTGGAAGAGGACACCGGCAACGAGCTGTCTACAAAGGAACAGATCTCACGCAATAGCAAAGCTCTGGAAGAGAAGTATGTCGCAGAGCTGCAGCTGGAACGGCTGAAGAAAGATGGCGAGGTGAGAGGGTCAATTAATAGGTTCAAGACAAGCGACTACGTCAAAGAAGCCAAGCAGCTGCTGAAAGTGCAGAAGGCTTACCACCAGCTGGATCAGAGCTTCATCGATACTTATATCGACCTGCTGGAGACTCGGAGAACCTACTATGAGGGACCAGGAGAAGGGAGCCCCTTCGGATGGAAAGACATCAAGGAATGGTACGAGATGCTGATGGGACATTGCACCTATTTTCCAGAAGAGCTGAGAAGCGTCAAGTACGCTTATAACGCAGATCTGTACAACGCCCTGAATGACCTGAACAACCTGGTCATCACCAGGGATGAAAACGAGAAACTGGAATACTATGAGAAGTTCCAGATCATCGAAAACGTGTTTAAGCAGAAGAAAAAGCCTACACTGAAACAGATTGCTAAGGAGATCCTGGTCAACGAAGAGGACATCAAGGGCTACCGGGTGACAAGCACTGGAAAACCAGAGTTCACCAATCTGAAAGTGTATCACGATATTAAGGACATCACAGCACGGAAAGAAATCATTGAGAACGCCGAACTGCTGGATCAGATTGCTAAGATCCTGACTATCTACCAGAGCTCCGAGGACATCCAGGAAGAGCTGACTAACCTGAACAGCGAGCTGACCCAGGAAGAGATCGAACAGATTAGTAATCTGAAGGGGTACACCGGAACACACAACCTGTCCCTGAAAGCTATCAATCTGATTCTGGATGAGCTGTGGCATACAAACGACAATCAGATTGCAATCTTTAACCGGCTGAAGCTGGTCCCAAAAAAGGTGGACCTGAGTCAGCAGAAAGAGATCCCAACCACACTGGTGGACGATTTCATTCTGTCACCCGTGGTCAAGCGGAGCTTCATCCAGAGCATCAAAGTGATCAACGCCATCATCAAGAAGTACGGCCTGCCCAATGATATCATTATCGAGCTGGCTAGGGAGAAGAACAGCAAGGACGCACAGAAGATGATCAATGAGATGCAGAAACGAAACCGGCAGACCAATGAACGCATTGAAGAGATTATCCGAACTACCGGGAAAGAGAACGCAAAGTACCTGATTGAAAAAATCAAGCTGCACGATATGCAGGAGGGAAAGTGTCTGTATTCTCTGGAGGCCATCCCCCTGGAGGACCTGCTGAACAATCCATTCAACTACGAGGTCGATCATATTATCCCCAGAAGCGTGTCCTTCGACAATTCCTTTAACAACAAGGTGCTGGTCAAGCAGGAAGAGAACTCTAAAAAGGGCAATAGGACTCCTTTCCAGTACCTGTCTAGTTCAGATTCCAAGATCTCTTACGAAACCTTTAAAAAGCACATTCTGAATCTGGCCAAAGGAAAGGGCCGCATCAGCAAGACCAAAAAGGAGTACCTGCTGGAAGAGCGGGACATCAACAGATTCTCCGTCCAGAAGGATTTTATTAACCGGAATCTGGTGGACACAAGATACGCTACTCGCGGCCTGATGAATCTGCTGCGATCCTATTTCCGGGTGAACAATCTGGATGTGAAAGTCAAGTCCATCAACGGCGGGTTCACATCTTTTCTGAGGCGCAAATGGAAGTTTAAAAAGGAGCGCAACAAAGGGTACAAGCACCATGCCGAAGATGCTCTGATTATCGCAAATGCCGACTTCATCTTTAAGGAGTGGAAAAAGCTGGACAAAGCCAAGAAAGTGATGGAGAACCAGATGTTCGAAGAGAAGCAGGCCGAATCTATGCCCGAAATCGAGACAGAACAGGAGTACAAGGAGATTTTCATCACTCCTCACCAGATCAAGCATATCAAGGATTTCAAGGACTACAAGTACTCTCACCGGGTGGATAAAAAGCCCAACAGAGAGCTGATCAATGACACCCTGTATAGTACAAGAAAAGACGATAAGGGGAATACCCTGATTGTGAACAATCTGAACGGACTGTACGACAAAGATAATGACAAGCTGAAAAAGCTGATCAACAAAAGTCCCGAGAAGCTGCTGATGTACCACCATGATCCTCAGACATATCAGAAACTGAAGCTGATTATGGAGCAGTACGGCGACGAGAAGAACCCACTGTATAAGTACTATGAAGAGACTGGGAACTACCTGACCAAGTATAGCAAAAAGGATAATGGCCCCGTGATCAAGAAGATCAAGTACTATGGGAACAAGCTGAATGCCCATCTGGACATCACAGACGATTACCCTAACAGTCGCAACAAGGTGGTCAAGCTGTCACTGAAGCCATACAGATTCGATGTCTATCTGGACAACGGCGTGTATAAATTTGTGACTGTCAAGAATCTGGATGTCATCAAAAAGGAGAACTACTATGAAGTGAATAGCAAGTGCTACGAAGAGGCTAAAAAGCTGAAAAAGATTAGCAACCAGGCAGAGTTCATCGCCTCCTTTTACAACAACGACCTGATTAAGATCAATGGCGAACTGTATAGGGTCATCGGGGTGAACAATGATCTGCTGAACCGCATTGAAGTGAATATGATTGACATCACTTACCGAGAGTATCTGGAAAACATGAATGATAAGCGCCCCCCTCGAATTATCAAAACAATTGCCTCTAAGACTCAGAGTATCAAAAAGTACTCAACCGACATTCTGGGAAACCTGTATGAGGTGAAGAGCAAAAAGCACCCTCAGATTATCAAAAAGGGC [SEQ ID NO: 11]

In certain embodiments, the RNA-guided nuclease is Cpf1. In certainembodiments, the amino acid sequence of a Cpf1 protein is set forth inSEQ ID NO: 13. In certain embodiments, the Cpf1 protein can comprise aninsertion such as a GX₆₋₁₀G insertion. In certain embodiments, theinsertion (relative to SEQ ID NO: 13) is positioned between amino acidpositions 147 and 148, anywhere between amino acid positions 484 and492, anywhere between amino acid positions 568 and 590, anywhere betweenamino acid positions 795 and 855, anywhere between amino acid positions1131 and 1140, or anywhere between amino acid positions 1160 and 1173.In certain embodiments, the insertion is positioned at or near theN-terminus of a Cpf1 peptide. In certain embodiments, the amino acidsequence of the Cpf1 protein comprising the insertion has at least 95%sequence identity (e.g. 95%, 96%, 97%, 98%, 99% or greater identity) toSEQ ID NO: 13.

[SEQ ID NO: 13] MTQFEGFTNLYQVSKTLRFELIPQGKTLKHIQEQGFIEEDKARNDHYKELKPIIDRIYKTYADQCLQLVQLDWENLSAAIDSYRKEKTEETRNALIEEQATYRNAIHDYFIGRTDNLTDAINKRHAEIYKGLFKAELFNGKVLKQLGTVTTTEHENALLRSFDKFTTYFSGFYENRKNVFSAEDISTAIPHRIVQDNFPKFKENCHIFTRLITAVPSLREHFENVKKAIGIFVSTSIEEVFSFPFYNQLLTQTQIDLYNQLLGGISREAGTEKIKGLNEVLNLAIQKNDETAHIIASLPHRFIPLFKQILSDRNTLSFILEEFKSDEEVIQSFCKYKTLLRNENVLETAEALFNELNSIDLTHIFISHKKLETISSALCDHWDTLRNALYERRISELTGKITKSAKEKVQRSLKHEDINLQEIISAAGKELSEAFKQKTSEILSHAHAALDQPLPTTLKKQEEKEILKSQLDSLLGLYHLLDWFAVDESNEVDPEFSARLTGIKLEMEPSLSFYNKARNYATKKPYSVEKFKLNFQMPTLASGWDVNKEKNNGAILFVKNGLYYLGIMPKQKGRYKALSFEPTEKTSEGFDKMYYDYFPDAAKMIPKCSTQLKAVTAHFQTHTTPILLSNNFIEPLEITKEIYDLNNPEKEPKKFQTAYAKKTGDQKGYREALCKWIDFTRDFLSKYTKTTSIDLSSLRPSSQYKDLGEYYAELNPLLYHISFQRIAEKEIMDAVETGKLYLFQIYNKDFAKGHHGKPNLHTLYWTGLFSPENLAKTSIKLNGQAELFYRPKSRMKRMAHRLGEKMLNKKLKDQKTPIPDTLYQELYDYVNHRLSHDLSDEARALLPNVITKEVSHEIIKDRRFTSDKFFFHVPITLNYQAANSPSKFNQRVNAYLKEHPETPIIGIDRGERNLIYITVIDSTGKILEQRSLNTIQQFDYQKKLDNREKERVAARQAWSVVGTIKDLKQGYLSQVIHEIVDLMIHYQAVVVLANLNFGFKSKRTGIAEKAVYQQFEKMLIDKLNCLVLKDYPAEKVGGVLNPYQLTDQFTSFAKMGTQSGFLFYVPAPYTSKIDPLTGFVDPFVWKTIKNHESRKHFLEGFDFLHYDVKTGDFILHFKMNRNLSFQRGLPGFMPAWDIVFEKNETQFDAKGTPFIAGKRIVPVIENHRFTGRYRDLYPANELIALLEEKGIVFRDGSNILPKLLENDDSHAIDTMVALIRSVLQMRNSNAATGEDYINSPVRDLNGVCFDSRFQNPEWPMDADANGAYHIALKGQLLLNHLKESKDLKLQNGISNQDWLA YIQELRN

In certain embodiments, an isolated nucleic acid sequence encoding aCpf1 protein is set forth in SEQ ID NO: 14. In certain embodiments, theisolated Cpf1 nucleic acid can comprise an insertion such as an N24-36insertion. In certain embodiments, the insertion (relative to SEQ ID NO:14) is positioned between nucleic acid positions 441 and 442, anywherebetween nucleic acid positions 1452 and 1474, anywhere between nucleicacid positions 1704 and 1768, anywhere between nucleic acid positions2385 and 2563, anywhere between nucleic acid positions 3393 and 3418, oranywhere between nucleic acid positions 3480 and 3517. In certainembodiments, the insertion does not alter the reading frame of theisolated Cpf1 nucleic acid. In certain embodiments, the insertion ispositioned at or near the N-terminus of a Cpf1 peptide. In certainembodiments, the nucleic acid sequence of the Cpf1 protein comprisingthe insertion has at least 95% (e.g. 95%, 96%, 97%, 98%, 99% or greateridentity) sequence identity to SEQ ID NO: 14. Isolated nucleic acidsaccording to this aspect of this disclosure are optionally incorporatedinto vectors such as plasmids, viral vectors, naked DNA vectors, etc. Insome instances, an adeno-associated virus (AAV) vector incorporatesisolated nucleic acids according to this aspect of the disclosure. Incertain embodiments, a target site for the gRNA is within the vectorbackbone. The vectors can be used to alter both a cellular endogenoustarget gene and the RNA-guided nuclease expression.

[SEQ ID NO: 14] ATGACACAGTTCGAGGGCTTTACCAACCTGTATCAGGTGAGCAAGACACTGCGGTTTGAGCTGATCCCACAGGGCAAGACCCTGAAGCACATCCAGGAGCAGGGCTTCATCGAGGAGGACAAGGCCCGCAATGATCACTACAAGGAGCTGAAGCCCATCATCGATCGGATCTACAAGACCTATGCCGACCAGTGCCTGCAGCTGGTGCAGCTGGATTGGGAGAACCTGAGCGCCGCCATCGACTCCTATAGAAAGGAGAAAACCGAGGAGACAAGGAACGCCCTGATCGAGGAGCAGGCCACATATCGCAATGCCATCCACGACTACTTCATCGGCCGGACAGACAACCTGACCGATGCCATCAATAAGAGACACGCCGAGATCTACAAGGGCCTGTTCAAGGCCGAGCTGTTTAATGGCAAGGTGCTGAAGCAGCTGGGCACCGTGACCACAACCGAGCACGAGAACGCCCTGCTGCGGAGCTTCGACAAGTTTACAACCTACTTCTCCGGCTTTTATGAGAACAGGAAGAACGTGTTCAGCGCCGAGGATATCAGCACAGCCATCCCACACCGCATCGTGCAGGACAACTTCCCCAAGTTTAAGGAGAATTGTCACATCTTCACACGCCTGATCACCGCCGTGCCCAGCCTGCGGGAGCACTTTGAGAACGTGAAGAAGGCCATCGGCATCTTCGTGAGCACCTCCATCGAGGAGGTGTTTTCCTTCCCTTTTTATAACCAGCTGCTGACACAGACCCAGATCGACCTGTATAACCAGCTGCTGGGAGGAATCTCTCGGGAGGCAGGCACCGAGAAGATCAAGGGCCTGAACGAGGTGCTGAATCTGGCCATCCAGAAGAATGATGAGACAGCCCACATCATCGCCTCCCTGCCACACAGATTCATCCCCCTGTTTAAGCAGATCCTGTCCGATAGGAACACCCTGTCTTTCATCCTGGAGGAGTTTAAGAGCGACGAGGAAGTGATCCAGTCCTTCTGCAAGTACAAGACACTGCTGAGAAACGAGAACGTGCTGGAGACAGCCGAGGCCCTGTTTAACGAGCTGAACAGCATCGACCTGACACACATCTTCATCAGCCACAAGAAGCTGGAGACAATCAGCAGCGCCCTGTGCGACCACTGGGATACACTGAGGAATGCCCTGTATGAGCGGAGAATCTCCGAGCTGACAGGCAAGATCACCAAGTCTGCCAAGGAGAAGGTGCAGCGCAGCCTGAAGCACGAGGATATCAACCTGCAGGAGATCATCTCTGCCGCAGGCAAGGAGCTGAGCGAGGCCTTCAAGCAGAAAACCAGCGAGATCCTGTCCCACGCACACGCCGCCCTGGATCAGCCACTGCCTACAACCCTGAAGAAGCAGGAGGAGAAGGAGATCCTGAAGTCTCAGCTGGACAGCCTGCTGGGCCTGTACCACCTGCTGGACTGGTTTGCCGTGGATGAGTCCAACGAGGTGGACCCCGAGTTCTCTGCCCGGCTGACCGGCATCAAGCTGGAGATGGAGCCTTCTCTGAGCTTCTACAACAAGGCCAGAAATTATGCCACCAAGAAGCCCTACTCCGTGGAGAAGTTCAAGCTGAACTTTCAGATGCCTACACTGGCCTCTGGCTGGGACGTGAATAAGGAGAAGAACAATGGCGCCATCCTGTTTGTGAAGAACGGCCTGTACTATCTGGGCATCATGCCAAAGCAGAAGGGCAGGTATAAGGCCCTGAGCTTCGAGCCCACAGAGAAAACCAGCGAGGGCTTTGATAAGATGTACTATGACTACTTCCCTGATGCCGCCAAGATGATCCCAAAGTGCAGCACCCAGCTGAAGGCCGTGACAGCCCACTTTCAGACCCACACAACCCCCATCCTGCTGTCCAACAATTTCATCGAGCCTCTGGAGATCACAAAGGAGATCTACGACCTGAACAATCCTGAGAAGGAGCCAAAGAAGTTTCAGACAGCCTACGCCAAGAAAACCGGCGACCAGAAGGGCTACAGAGAGGCCCTGTGCAAGTGGATCGACTTCACAAGGGATTTTCTGTCCAAGTATACCAAGACAACCTCTATCGATCTGTCTAGCCTGCGGCCATCCTCTCAGTATAAGGACCTGGGCGAGTACTATGCCGAGCTGAATCCCCTGCTGTACCACATCAGCTTCCAGAGAATCGCCGAGAAGGAGATCATGGATGCCGTGGAGACAGGCAAGCTGTACCTGTTCCAGATCTATAACAAGGACTTTGCCAAGGGCCACCACGGCAAGCCTAATCTGCACACACTGTATTGGACCGGCCTGTTTTCTCCAGAGAACCTGGCCAAGACAAGCATCAAGCTGAATGGCCAGGCCGAGCTGTTCTACCGCCCTAAGTCCAGGATGAAGAGGATGGCACACCGGCTGGGAGAGAAGATGCTGAACAAGAAGCTGAAGGATCAGAAAACCCCAATCCCCGACACCCTGTACCAGGAGCTGTACGACTATGTGAATCACAGACTGTCCCACGACCTGTCTGATGAGGCCAGGGCCCTGCTGCCCAACGTGATCACCAAGGAGGTGTCTCACGAGATCATCAAGGATAGGCGCTTTACCAGCGACAAGTTCTTTTTCCACGTGCCTATCACACTGAACTATCAGGCCGCCAATTCCCCATCTAAGTTCAACCAGAGGGTGAATGCCTACCTGAAGGAGCACCCCGAGACACCTATCATCGGCATCGATCGGGGCGAGAGAAACCTGATCTATATCACAGTGATCGACTCCACCGGCAAGATCCTGGAGCAGCGGAGCCTGAACACCATCCAGCAGTTTGATTACCAGAAGAAGCTGGACAACAGGGAGAAGGAGAGGGTGGCAGCAAGGCAGGCCTGGTCTGTGGTGGGCACAATCAAGGATCTGAAGCAGGGCTATCTGAGCCAGGTCATCCACGAGATCGTGGACCTGATGATCCACTACCAGGCCGTGGTGGTGCTGGCGAACCTGAATTTCGGCTTTAAGAGCAAGAGGACCGGCATCGCCGAGAAGGCCGTGTACCAGCAGTTCGAGAAGATGCTGATCGATAAGCTGAATTGCCTGGTGCTGAAGGACTATCCAGCAGAGAAAGTGGGAGGCGTGCTGAACCCATACCAGCTGACAGACCAGTTCACCTCCTTTGCCAAGATGGGCACCCAGTCTGGCTTCCTGTTTTACGTGCCTGCCCCATATACATCTAAGATCGATCCCCTGACCGGCTTCGTGGACCCCTTCGTGTGGAAAACCATCAAGAATCACGAGAGCCGCAAGCACTTCCTGGAGGGCTTCGACTTTCTGCACTACGACGTGAAAACCGGCGACTTCATCCTGCACTTTAAGATGAACAGAAATCTGTCCTTCCAGAGGGGCCTGCCCGGCTTTATGCCTGCATGGGATATCGTGTTCGAGAAGAACGAGACACAGTTTGACGCCAAGGGCACCCCTTTCATCGCCGGCAAGAGAATCGTGCCAGTGATCGAGAATCACAGATTCACCGGCAGATACCGGGACCTGTATCCTGCCAACGAGCTGATCGCCCTGCTGGAGGAGAAGGGCATCGTGTTCAGGGATGGCTCCAACATCCTGCCAAAGCTGCTGGAGAATGACGATTCTCACGCCATCGACACCATGGTGGCCCTGATCCGCAGCGTGCTGCAGATGCGGAACTCCAATGCCGCCACAGGCGAGGACTATATCAACAGCCCCGTGCGCGATCTGAATGGCGTGTGCTTCGACTCCCGGTTTCAGAACCCAGAGTGGCCCATGGACGCCGATGCCAATGGCGCCTACCACATCGCCCTGAAGGGCCAGCTGCTGCTGAATCACCTGAAGGAGAGCAAGGATCTGAAGCTGCAGAACGGCATCTCCAATCAGGACTGGCTGGCC TACATCCAGGAGCTGCGCAAC

Skilled artisans will be aware that the exemplary sequences presentedherein may be modified in ways that do not affect the operatingprinciples of the genome editing systems they embody. Accordingly,modified nucleotide or amino acid sequences that are truncated, fused toother sequences, or otherwise modified tohave >50%, >60%, >70%, >80%, >85%, >90%, >91%, >92%, >93%, >94%, >95%, >96%, >97%, >98%or >99% sequence identity relative to the sequences presented herein arewithin the scope of this disclosure. So too are amino acid or nucleicacid sequences differing by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20 ormore residues from the sequences presented herein.

Turning next to the selection of inserts that will minimize disruptionof nuclease structure, many of the inserts within the scope of thisdisclosure have been engineered to satisfy one or more of the followingrequirements: (i) the insert includes, at its 3′ and 5′ ends,3-nucleotide codons for glycine or another small, flexible residue(e.g., alanine or valine), and encodes an amino acid sequence such as:G-[X]₆₋₁₀-G, where “X” denotes any amino acid, subject to theconstraints set forth here; (ii) the insert does not introduce a stopcodon, splice donor or acceptor, or other undesirable domain in thecoding sequence; (iii) X is characterized by a hydrophilicity orhydrophobicity that will not disrupt the folding of the engineeredprotein or its final structure (e.g. phenylalanine); and (iv) X is notbulky (e.g. tryptophan), and is not a cysteine, proline or other aminoacid that could disrupt the structure of the Cas9 by introducing a bendor causing steric interference with the surrounding protein, forming asulfur bridge, etc.

In certain cases, inserts according to this disclosure can be generatedaccording to the following heuristic:

-   -   1. For a target site (protospacer and PAM) within a cellular        gene target of interest, identify all possible amino acid        sequences that may be encoded by the target site sequence in all        six possible reading frames;    -   2. Discard any nucleotide sequence reading frames that do not        meet the design criteria set forth above (e.g., that encode a        stop codon, or that encode peptides that would likely disrupt        the structure of the surrounding protein due to hydrophobicity,        bulk, etc.;    -   3. For each nucleotide sequence that is not discarded in step 2,        -   a. add glycine codons to the 3′ and 5′ ends of the target            site,        -   b. if necessary, insert on the 5′ end of the sequence            between the glycine codon and the target site, one or two            nucleotides to shift the target site sequence into a desired            reading frame; and        -   c. if necessary, insert, on the 3′ end of the sequence            between the target site and the glycine codon, one or two            nucleotides to keep the 3′ glycine codon and the subsequent            peptide sequence in frame.

It should be noted that the inserts of the present disclosure arebroadly compatible with RNA-guided nucleases, including withoutlimitation Cas9, Cpf1, and other Class 2 nucleases and the variousorthologs thereof, and nucleic acids encoding the same. In certainembodiments, the RNA-guided nuclease is Cas9. In certain embodiments,the RNA-guided nuclease is Cpf1. While certain examples of thisdisclosure focus on the use of inserts to regulate expression of S.aureus Cas9, the skilled artisan will appreciate that an insert of thisdisclosure may be adapted for use with other nucleases or orthologs. Byway of example, an insert may be adapted for use in another nuclease orortholog by (i) selecting an appropriate target site comprising a PAMsequence recognized by the nuclease or ortholog, and (ii) selecting aninsertion site that is within a peptide loop that is (a) located on asurface of the nuclease protein, and/or (b) predicted to tolerate theinsertion of the insert without alterations in folding or structure.

In use, the engineered nucleic acids according to this disclosuresimultaneously provide a template for transcription and expression ofgenome editing system components and a substrate for cleavage or otherediting by genome editing systems once expressed. In many (though notnecessarily all) embodiments, cleavage of the engineered nucleic aciddecreases or eliminates expression of one or more genome editing systemcomponents encoded by the engineered nucleic acid. Alternatively, oradditionally, cleavage of the engineered nucleic acids can result in theformation of indel mutations that decrease the function of the genomeediting system components. These outcomes, in turn, can provide atemporal limit to the genome editing activity caused by delivery of theengineered nucleic acids as compared to non-engineered nucleotidesencoding similar components. For example, where a nucleic acid vectorencoding a RNA-guided nuclease and gRNA under the control ofconstitutive promoters would be expected to drive ongoing, constitutivegenome editing activity, the inclusion of an ogRNA target site in thesame vector (whether in the backbone or the RNA-guided nuclease codingsequence) will result in a limited period of high expression of systemcomponents and a transient peak in genome editing activity, which willdecrease as copies of the vector within each cell are cleaved andinactivated, over a period of hours, days, or weeks. It will be clear tothe skilled artisan that temporal limitation of genome editing activityusing the transiently active genome editing systems described herein canbe advantageous in certain settings, for instance to limit the potentialfor off-target cutting, or to limit any potential cellular response tothe genome editing system components.

In certain embodiments, the activity of the RNA-guided nuclease can bemodulated via the nature of the ogRNA target sequence inserted intoeither the vector backbone or the RNA-guided nuclease coding sequence.For example, if the ogRNA target sequence comprises a consensus PAMsequence, the RNA-guided nuclease will edit the nucleic acid encodingthe RNA-guided nuclease at a higher efficiency than a target sequencecomprising a sub-optimal PAM. Accordingly, if a consensus PAM sequenceis employed, expression of the RNA-guided nuclease will reflect a burstdose, while if a sub-optimal PAM sequence is employed, expression of theRNA-guided nuclease will reflect an extended dose. Exemplary consensusand sub-optimal PAM sequences for S. aureus Cas9 are listed in Table 5.

TABLE 5 Consensus and sub-optimal S. aureus Cas9 PAM sequences PAMDescription NNGRRT Consensus S. aureus PAM NNGYRT Sub-optimal PAM -substitute Y at R1 NNGRYT Sub-optimal PAM - substitute Y at R2 NNGYYTSub-optimal PAM - substitutions at R1, R2 NNGRRV Sub-optimal PAM -substitution of V for T NNGYRV Sub-optimal PAM - substitutions at R1, TNNGRYV Sub-optimal PAM - substitutions at R2, T NNHRRT Sub-optimal PAM -substitution of H for G NNHYRT Sub-optimal PAM - substitution of H forG, R1 NNHRYT Sub-optimal PAM - substitution of H for G, R2 NNHRRVSub-optimal PAM - substitution of H for G, V for T NNHYRV Sub-optimalPAM - substitution of H for G, R1, V for T NNHRYV Sub-optimal PAM -substitution of H for G, R2, V for T NNHYYV Sub-optimal PAM -substitution of H for G, R1, R2, V for T

This overview has focused on a handful of exemplary embodiments thatillustrate the principles of certain engineered nucleic acid vectors andengineered RNA-guided nucleases. For clarity, however, this disclosureencompasses modifications and variations that will be evident to thoseof skill in the art. For example, editing of the nucleic acid encodingthe RNA-guided nuclease and the nuclei acid encoding the cellularendogenous target gene, as described herein, can be simultaneous orconcomitant, however there is not necessarily a temporal restriction ofsuch editing. With that in mind, the following disclosure is intended toillustrate the operating principles of genome editing systems moregenerally. What follows should not be understood as limiting, but ratherillustrative of certain principles of genome editing systems, which, incombination with the instant disclosure, will inform those of skill inthe art about additional implementations of and modifications that arewithin the scope of this disclosure.

Genome Editing Systems

The term “genome editing system” refers to any system having RNA-guidedDNA editing activity. Genome editing systems of the present disclosureinclude at least two components adapted from naturally occurring CRISPRsystems: a guide RNA (gRNA) and an RNA-guided nuclease. These twocomponents form a complex that is capable of associating with a specificnucleic acid sequence and editing the DNA in or around that nucleic acidsequence, for instance by making one or more of a single strand break(an SSB or nick), a double strand break (a DSB) and/or a point mutation.In certain embodiments, the genome editing system is a transientlyactive genome editing system. In certain embodiments, the genome editingsystem can alter both a cellular endogenous target gene and theRNA-guided-nuclease expression. In certain embodiments, thegRNA/RNA-guided nuclease complex can cleave both the nucleic acidencoding the RNA-guided nuclease and the nucleic acid encoding thecellular endogenous target gene.

Naturally occurring CRISPR systems are organized evolutionarily into twoclasses and five types (Makarova et al. Nat Rev Microbiol. 2011 June;9(6): 467-477 (Makarova), incorporated by reference herein), and whilegenome editing systems of the present disclosure may adapt components ofany type or class of naturally occurring CRISPR system, the embodimentspresented herein are generally adapted from Class 2, and type II or VCRISPR systems. Class 2 systems, which encompass types II and V, arecharacterized by relatively large, multidomain RNA-guided nucleaseproteins (e.g., Cas9 or Cpf1) and one or more guide RNAs (e.g., a crRNAand, optionally, a tracrRNA) that form ribonucleoprotein (RNP) complexesthat associate with (i.e. target) and cleave specific loci complementaryto a targeting (or spacer) sequence of the crRNA. Genome editing systemsaccording to the present disclosure similarly target and edit cellularDNA sequences, but differ significantly from CRISPR systems occurring innature. For example, the unimolecular guide RNAs described herein do notoccur in nature, and both guide RNAs and RNA-guided nucleases accordingto this disclosure may incorporate any number of non-naturally occurringmodifications.

Genome editing systems can be implemented (e.g. administered ordelivered to a cell or a subject) in a variety of ways, and differentimplementations may be suitable for distinct applications. For instance,a genome editing system is implemented, in certain embodiments, as aprotein/RNA complex (a ribonucleoprotein, or RNP), which can be includedin a pharmaceutical composition that optionally includes apharmaceutically acceptable carrier and/or an encapsulating agent, suchas a lipid or polymer micro- or nano-particle, micelle, liposome, etc.In certain embodiments, a genome editing system is implemented as one ormore nucleic acids encoding the RNA-guided nuclease and guide RNAcomponents described above (optionally with one or more additionalcomponents); in certain embodiments, the genome editing system isimplemented as one or more vectors comprising such nucleic acids, forinstance a viral vector such as an adeno-associated virus; and incertain embodiments, the genome editing system is implemented as acombination of any of the foregoing. Additional or modifiedimplementations that operate according to the principles set forthherein will be apparent to the skilled artisan and are within the scopeof this disclosure.

It should be noted that the genome editing systems of the presentdisclosure can be targeted to a single specific nucleotide sequence, ormay be targeted to—and capable of editing in parallel—two or morespecific nucleotide sequences through the use of two or more guide RNAs.The use of multiple gRNAs is referred to as “multiplexing” throughoutthis disclosure, and can be employed to target multiple, unrelatedtarget sequences of interest, or to form multiple SSBs or DSBs within asingle target domain and, in some cases, to generate specific editswithin such target domain. For example, International Patent PublicationNo. WO 2015/138510 by Maeder et al. (Maeder), which is incorporated byreference herein, describes a genome editing system for correcting apoint mutation (C.2991+1655A to G) in the human CEP290 gene that resultsin the creation of a cryptic splice site, which in turn reduces oreliminates the function of the gene. The genome editing system of Maederutilizes two guide RNAs targeted to sequences on either side of (i.e.flanking) the point mutation, and forms DSBs that flank the mutation.This, in turn, promotes deletion of the intervening sequence, includingthe mutation, thereby eliminating the cryptic splice site and restoringnormal gene function.

As another example, WO 2016/073990 by Cotta-Ramusino, et al.(“Cotta-Ramusino”), incorporated by reference herein, describes a genomeediting system that utilizes twogRNAs in combination with a Cas9 nickase(a Cas9 that makes a single strand nick such as S. pyogenes D10A), anarrangement termed a “dual-nickase system.” The dual-nickase system ofCotta-Ramusino is configured to make two nicks on opposite strands of asequence of interest that are offset by one or more nucleotides, whichnicks combine to create a double strand break having an overhang (5′ inthe case of Cotta-Ramusino, though 3′ overhangs are also possible). Theoverhang, in turn, can facilitate homology directed repair events insome circumstances. And, as another example, WO 2015/070083 byPalestrant et al. (“Palestrant”, incorporated by reference herein)describes a gRNA targeted to a nucleotide sequence encoding Cas9(referred to as a “governing RNA”), which can be included in a genomeediting system comprising one or more additional gRNAs to permittransient expression of a Cas9 that might otherwise be constitutivelyexpressed, for example in some virally transduced cells. Thesemultiplexing applications are intended to be exemplary, rather thanlimiting, and the skilled artisan will appreciate that otherapplications of multiplexing are generally compatible with the genomeediting systems described here.

Genome editing systems can, in some instances, form double strand breaksthat are repaired by cellular DNA double-strand break mechanisms such asNHEJ or HDR. These mechanisms are described throughout the literature,for example by Davis & Maizels, PNAS, 111(10):E924-932, March 11, 2014(Davis) (describing Alt-HDR); Frit et al. DNA Repair 17(2014) 81-97(Frit) (describing Alt-NHEJ); and Iyama and Wilson III, DNA Repair(Amst.) 2013-August; 12(8): 620-636 (Iyama) (describing canonical HDRand NHEJ pathways generally).

Where genome editing systems operate by forming DSBs, such systemsoptionally include one or more components that promote or facilitate aparticular mode of double-strand break repair or a particular repairoutcome. For instance, Cotta-Ramusino also describes genome editingsystems in which a single-stranded oligonucleotide “donor template” isadded; the donor template is incorporated into a target region ofcellular DNA that is cleaved by the genome editing system, and canresult in a change in the target sequence.

In certain embodiments, genome editing systems modify a target sequence,or modify expression of a gene in or near the target sequence, withoutcausing single- or double-strand breaks. For example, a genome editingsystem may include an RNA-guided nuclease fused to a functional domainthat acts on DNA, thereby modifying the target sequence or itsexpression. As one example, an RNA-guided nuclease can be connected to(e.g. fused to) a cytidine deaminase functional domain, and may operateby generating targeted C-to-A substitutions. Exemplarynuclease/deaminase fusions are described in Komor et al. Nature 533,420-424 (19 May 2016) (“Komor”), which is incorporated by reference.Alternatively, a genome editing system may utilize acleavage-inactivated (i.e. a “dead”) nuclease, such as a dead Cas9(dCas9), and may operate by forming stable complexes on one or moretargeted regions of cellular DNA, thereby interfering with functionsinvolving the targeted region(s) including, without limitation, mRNAtranscription, chromatin remodeling, etc.

Guide RNA (gRNA) Molecules

The terms “guide RNA” and “gRNA” refer to any nucleic acid that promotesthe specific association (or “targeting”) of an RNA-guided nuclease suchas a Cas9 or a Cpf1 to a target sequence such as a genomic or episomalsequence in a cell. gRNAs can be unimolecular (comprising a single RNAmolecule, and referred to alternatively as chimeric), or modular(comprising more than one, and typically two, separate RNA molecules,such as a crRNA and a tracrRNA, which are usually associated with oneanother, for instance by duplexing). gRNAs and their component parts aredescribed throughout the literature, for instance in Briner et al.(Molecular Cell 56(2), 333-339, Oct. 23, 2014 (Briner), which isincorporated by reference), and in Cotta-Ramusino.

In bacteria and archaea, type II CRISPR systems generally comprise anRNA-guided nuclease protein such as Cas9, a CRISPR RNA (crRNA) thatincludes a 5′ region that is complementary to a foreign sequence, and atrans-activating crRNA (tracrRNA) that includes a 5′ region that iscomplementary to, and forms a duplex with, a 3′ region of the crRNA.While not intending to be bound by any theory, it is thought that thisduplex facilitates the formation of—and is necessary for the activityof—the Cas9/gRNA complex. As type II CRISPR systems were adapted for usein gene editing, it was discovered that the crRNA and tracrRNA could bejoined into a single unimolecular or chimeric guide RNA, for instance,but not by way of limitation, by means of a four nucleotide (e.g. GAAA)“tetraloop” or “linker” sequence bridging complementary regions of thecrRNA (at its 3′ end) and the tracrRNA (at its 5′ end). (Mali et al.Science. 2013 Feb. 15; 339(6121): 823-826 (“Mali”); Jiang et al. NatBiotechnol. 2013 March; 31(3): 233-239 (“Jiang”); and Jinek et al., 2012Science August 17; 337(6096): 816-821 (“Jinek”), all of which areincorporated by reference herein.)

Guide RNAs, whether unimolecular or modular, include a “targetingdomain” that is fully or partially complementary to a target domainwithin a target sequence, such as a DNA sequence in the genome of a cellwhere editing is desired. Targeting domains are referred to by variousnames in the literature, including without limitation “guide sequences”(Hsu et al., Nat Biotechnol. 2013 September; 31(9): 827-832, (“Hsu”),incorporated by reference herein), “complementarity regions”(Cotta-Ramusino), “spacers” (Briner) and generically as “crRNAs”(Jiang). Irrespective of the names they are given, targeting domains aretypically 10-30 nucleotides in length, and in certain embodiments are16-24 nucleotides in length (for instance, 16, 17, 18, 19, 20, 21, 22,23 or 24 nucleotides in length), and are at or near the 5′ terminus ofin the case of a Cas9 gRNA, and at or near the 3′ terminus in the caseof a Cpf1 gRNA.

In addition to the targeting domains, gRNAs typically (but notnecessarily, as discussed below) include a plurality of domains that mayinfluence the formation or activity of gRNA/Cas9 complexes. Forinstance, as mentioned above, the duplexed structure formed by first andsecondary complementarity domains of a gRNA (also referred to as arepeat:anti-repeat duplex) interacts with the recognition (REC) lobe ofCas9 and can mediate the formation of Cas9/gRNA complexes. (Nishimasu etal., Cell 156, 935-949, Feb. 27, 2014 (Nishimasu 2014) and Nishimasu etal., Cell 162, 1113-1126, Aug. 27, 2015 (Nishimasu 2015), bothincorporated by reference herein). It should be noted that the firstand/or second complementarity domains may contain one or more poly-Atracts, which can be recognized by RNA polymerases as a terminationsignal. The sequence of the first and second complentarity domains are,therefore, optionally modified to eliminate these tracts and promote thecomplete in vitro transcription of gRNAs, for instance through the useof A-G swaps as described in Briner, or A-U swaps. These and othersimilar modifications to the first and second complementarity domainsare within the scope of the present disclosure.

Along with the first and second complementarity domains, Cas9 gRNAstypically include two or more additional duplexed regions that areinvolved in nuclease activity in vivo but not necessarily in vitro.(Nishimasu 2015). A first stem-loop one near the 3′ portion of thesecond complementarity domain is referred to variously as the “proximaldomain,” (Cotta-Ramusino) “stem loop 1” (Nishimasu 2014 and 2015) andthe “nexus” (Briner). One or more additional stem loop structures aregenerally present near the 3′ end of the gRNA, with the number varyingby species: S. pyogenes gRNAs typically include two 3′ stem loops (for atotal of four stem loop structures including the repeat:anti-repeatduplex), while S. aureus and other species have only one (for a total ofthree stem loop structures). A description of conserved stem loopstructures (and gRNA structures more generally) organized by species isprovided in Briner.

While the foregoing description has focused on gRNAs for use with Cas9,it should be appreciated that other RNA-guided nucleases have been (ormay in the future be) discovered or invented which utilize gRNAs thatdiffer in some ways from those described to this point. For instance,Cpf1 (“CRISPR from Prevotella and Franciscella 1”) is a recentlydiscovered RNA-guided nuclease that does not require a tracrRNA tofunction. (Zetsche et al., 2015, Cell 163, 759-771 Oct. 22, 2015(Zetsche I), incorporated by reference herein). A gRNA for use in a Cpf1genome editing system generally includes a targeting domain and acomplementarity domain (alternately referred to as a “handle”). Itshould also be noted that, in gRNAs for use with Cpf1, the targetingdomain is usually present at or near the 3′ end, rather than the 5′ endas described above in connection with Cas9 gRNAs (the handle is at ornear the 5′ end of a Cpf1 gRNA).

Those of skill in the art will appreciate, however, that althoughstructural differences may exist between gRNAs from differentprokaryotic species, or between Cpf1 and Cas9 gRNAs, the principles bywhich gRNAs operate are generally consistent. Because of thisconsistency of operation, gRNAs can be defined, in broad terms, by theirtargeting domain sequences, and skilled artisans will appreciate that agiven targeting domain sequence can be incorporated in any suitablegRNA, including a unimolecular or modular gRNA, or a gRNA that includesone or more chemical modifications and/or sequential modifications(substitutions, additional nucleotides, truncations, etc.). Thus, foreconomy of presentation in this disclosure, gRNAs may be describedsolely in terms of their targeting domain sequences.

More generally, skilled artisans will appreciate that some aspects ofthe present disclosure relate to systems, methods and compositions thatcan be implemented using multiple RNA-guided nucleases. For this reason,unless otherwise specified, the term gRNA should be understood toencompass any suitable gRNA that can be used with any RNA-guidednuclease, and not only those gRNAs that are compatible with a particularspecies of Cas9 or Cpf1. By way of illustration, the term gRNA can, incertain embodiments, include a gRNA for use with any RNA-guided nucleaseoccurring in a Class 2 CRISPR system, such as a type II or type V orCRISPR system, or an RNA-guided nuclease derived or adapted therefrom.

gRNA Design

Methods for selection and validation of target sequences as well asoff-target analyses have been described previously, e.g., in Mali; Hsu;Fu et al., 2014 Nat biotechnol 32(3): 279-84, Heigwer et al., 2014 Natmethods 11(2):122-3; Bae et al. (2014) Bioinformatics 30(10): 1473-5;and Xiao A et al. (2014) Bioinformatics 30(8): 1180-1182. Each of thesereferences is incorporated by reference herein. As a non-limitingexample, gRNA design can involve the use of a software tool to optimizethe choice of potential target sequences corresponding to a user'starget sequence, e.g., to minimize total off-target activity across thegenome. While off-target activity is not limited to cleavage, thecleavage efficiency at each off-target sequence can be predicted, e.g.,using an experimentally-derived weighting scheme. These and other guideselection methods are described in detail in Maeder and Cotta-Ramusino.

gRNA Modifications

The activity, stability, or other characteristics of gRNAs can bealtered through the incorporation of certain modifications. As oneexample, transiently expressed or delivered nucleic acids can be proneto degradation by, e.g., cellular nucleases. Accordingly, the gRNAsdescribed herein can contain one or more modified nucleosides ornucleotides which introduce stability toward nucleases. While notwishing to be bound by theory it is also believed that certain modifiedgRNAs described herein can exhibit a reduced innate immune response whenintroduced into cells. Those of skill in the art will be aware ofcertain cellular responses commonly observed in cells, e.g., mammaliancells, in response to exogenous nucleic acids, particularly those ofviral or bacterial origin. Such responses, which can include inductionof cytokine expression and release and cell death, may be reduced oreliminated altogether by the modifications presented herein.

Certain exemplary modifications discussed in this section can beincluded at any position within a gRNA sequence including, withoutlimitation at or near the 5′ end (e.g., within 1-10, 1-5, or 1-2nucleotides of the 5′ end) and/or at or near the 3′ end (e.g., within1-10, 1-5, or 1-2 nucleotides of the 3′ end). In some cases,modifications are positioned within functional motifs, such as therepeat-anti-repeat duplex of a Cas9 gRNA, a stem loop structure of aCas9 or Cpf1 gRNA, and/or a targeting domain of a gRNA.

As one example, the 5′ end of a gRNA can include a eukaryotic mRNA capstructure or cap analog (e.g., a G(5)ppp(5)G cap analog, a m7G(5)ppp(5)Gcap analog, or a 3′-O-Me-m7G(5)ppp(5)G anti reverse cap analog (ARCA)),as shown below:

The cap or cap analog can be included during either chemical synthesisor in vitro transcription of the gRNA.

Along similar lines, the 5′ end of the gRNA can lack a 5′ triphosphategroup. For instance, in vitro transcribed gRNAs can bephosphatase-treated (e.g., using calf intestinal alkaline phosphatase)to remove a 5′ triphosphate group.

Another common modification involves the addition, at the 3′ end of agRNA, of a plurality (e.g., 1-10, 10-20, or 25-200) of adenine (A)residues referred to as a polyA tract. The polyA tract can be added to agRNA during chemical synthesis, following in vitro transcription using apolyadenosine polymerase (e.g., E. coli Poly(A)Polymerase), or in vivoby means of a polyadenylation sequence, as described in Maeder.

It should be noted that the modifications described herein can becombined in any suitable manner, e.g. a gRNA, whether transcribed invivo from a DNA vector, or in vitro transcribed gRNA, can include eitheror both of a 5′ cap structure or cap analog and a 3′ polyA tract.

Guide RNAs can be modified at a 3′ terminal U ribose. For example, thetwo terminal hydroxyl groups of the U ribose can be oxidized to aldehydegroups and a concomitant opening of the ribose ring to afford a modifiednucleoside as shown below:

wherein “U” can be an unmodified or modified uridine.

The 3′ terminal U ribose can be modified with a 2′3′ cyclic phosphate asshown below:

wherein “U” can be an unmodified or modified uridine.

Guide RNAs can contain 3′ nucleotides which can be stabilized againstdegradation, e.g., by incorporating one or more of the modifiednucleotides described herein. In certain embodiments, uridines can bereplaced with modified uridines, e.g., 5-(2-amino)propyl uridine, and5-bromo uridine, or with any of the modified uridines described herein;adenosines and guanosines can be replaced with modified adenosines andguanosines, e.g., with modifications at the 8-position, e.g., 8-bromoguanosine, or with any of the modified adenosines or guanosinesdescribed herein.

In certain embodiments, sugar-modified ribonucleotides can beincorporated into the gRNA, e.g., wherein the 2′ OH-group is replaced bya group selected from H, —OR, —R (wherein R can be, e.g., alkyl,cycloalkyl, aryl, aralkyl, heteroaryl or sugar), halo, —SH, —SR (whereinR can be, e.g., alkyl, cycloalkyl, aryl, aralkyl, heteroaryl or sugar),amino (wherein amino can be, e.g., NH₂; alkylamino, dialkylamino,heterocyclyl, arylamino, diarylamino, heteroarylamino,diheteroarylamino, or amino acid); or cyano (—CN). In certainembodiments, the phosphate backbone can be modified as described herein,e.g., with a phosphothioate (PhTx) group. In certain embodiments, one ormore of the nucleotides of the gRNA can each independently be a modifiedor unmodified nucleotide including, but not limited to 2′-sugarmodified, such as, 2′-O-methyl, 2′-O-methoxyethyl, or 2′-Fluoro modifiedincluding, e.g., 2′-F or 2′-O-methyl, adenosine (A), 2′-F or2′-O-methyl, cytidine (C), 2′-F or 2′-O-methyl, uridine (U), 2′-F or2′-O-methyl, thymidine (T), 2′-F or 2′-O-methyl, guanosine (G),2′-O-methoxyethyl-5-methyluridine (Teo), 2′-O-methoxyethyladenosine(Aeo), 2′O-methoxyethyl-5-methylcytidine (m5Ceo), and any combinationsthereof.

Guide RNAs can also include “locked” nucleic acids (LNA) in which the 2′OH-group can be connected, e.g., by a C1-6 alkylene or C1-6heteroalkylene bridge, to the 4′ carbon of the same ribose sugar. Anysuitable moiety can be used to provide such bridges, include withoutlimitation methylene, propylene, ether, or amino bridges; O-amino(wherein amino can be, e.g., NH₂; alkylamino, dialkylamino,heterocyclyl, arylamino, diarylamino, heteroarylamino, ordiheteroarylamino, ethylenediamine, or polyamino) and aminoalkoxy orO(CH₂)_(n)-amino (wherein amino can be, e.g., NH₂; alkylamino,dialkylamino, heterocyclyl, arylamino, diarylamino, heteroarylamino, ordiheteroarylamino, ethylenediamine, or polyamino).

In certain embodiments, a gRNA can include a modified nucleotide whichis multicyclic (e.g., tricyclo; and “unlocked” forms, such as glycolnucleic acid (GNA) (e.g., R-GNA or S-GNA, where ribose is replaced byglycol units attached to phosphodiester bonds), or threose nucleic acid(TNA, where ribose is replaced with α-L-threofuranosyl-(3′→2′)).

Generally, gRNAs include the sugar group ribose, which is a 5-memberedring having an oxygen. Exemplary modified gRNAs can include, withoutlimitation, replacement of the oxygen in ribose (e.g., with sulfur (S),selenium (Se), or alkylene, such as, e.g., methylene or ethylene);addition of a double bond (e.g., to replace ribose with cyclopentenyl orcyclohexenyl); ring contraction of ribose (e.g., to form a 4-memberedring of cyclobutane or oxetane); ring expansion of ribose (e.g., to forma 6- or 7-membered ring having an additional carbon or heteroatom, suchas for example, anhydrohexitol, altritol, mannitol, cyclohexanyl,cyclohexenyl, and morpholino that also has a phosphoramidate backbone).Although the majority of sugar analog alterations are localized to the2′ position, other sites are amenable to modification, including the 4′position. In certain embodiments, a gRNA comprises a 4′-S, 4′-Se or a4′-C-aminomethyl-2′-O-Me modification.

In certain embodiments, deaza nucleotides, e.g., 7-deaza-adenosine, canbe incorporated into the gRNA. In certain embodiments, O- andN-alkylated nucleotides, e.g., N6-methyl adenosine, can be incorporatedinto the gRNA. In certain embodiments, one or more or all of thenucleotides in a gRNA are deoxynucleotides.

RNA-guided Nucleases

RNA-guided nucleases according to the present disclosure include, butare not limited to, naturally-occurring Class 2 CRISPR nucleases such asCas9, and Cpf1, as well as other nucleases derived or obtainedtherefrom. In functional terms, RNA-guided nucleases are defined asthose nucleases that: (a) interact with (e.g. complex with) a gRNA; and(b) together with the gRNA, associate with, and optionally cleave ormodify, a target region of a DNA that includes (i) a sequencecomplementary to the targeting domain of the gRNA and, optionally, (ii)an additional sequence referred to as a “protospacer adjacent motif,” or“PAM,” which is described in greater detail below. As the followingexamples will illustrate, RNA-guided nucleases can be defined, in broadterms, by their PAM specificity and cleavage activity, even thoughvariations may exist between individual RNA-guided nucleases that sharethe same PAM specificity or cleavage activity. Skilled artisans willappreciate that some aspects of the present disclosure relate tosystems, methods and compositions that can be implemented using anysuitable RNA-guided nuclease having a certain PAM specificity and/orcleavage activity. For this reason, unless otherwise specified, the termRNA-guided nuclease should be understood as a generic term, and notlimited to any particular type (e.g. Cas9 vs. Cpf1), species (e.g. S.pyogenes vs. S. aureus) or variation (e.g. full-length vs. truncated orsplit; naturally-occurring PAM specificity vs. engineered PAMspecificity, etc.) of RNA-guided nuclease.

The PAM sequence takes its name from its sequential relationship to the“protospacer” sequence that is complementary to gRNA targeting domains(or “spacers”). Together with protospacer sequences, PAM sequencesdefine target regions or sequences for specific RNA-guided nuclease/gRNAcombinations.

Various RNA-guided nucleases may require different sequentialrelationships between PAMs and protospacers. In general, Cas9s recognizePAM sequences that are 3′ of the protospacer as visualized on the bottomor non-complementary strand:

Cpf1, on the other hand, generally recognizes PAM sequences that are 5′of the protospacer as visualized on the bottom or non-complementarystrand:

In addition to recognizing specific sequential orientations of PAMs andprotospacers, RNA-guided nucleases can also recognize specific PAMsequences. S. aureus Cas9, for instance, recognizes a PAM sequence ofNNGRRT or NNGRRV, wherein the N residues are immediately 3′ of theregion recognized by the gRNA targeting domain. S. pyogenes Cas9recognizes NGG PAM sequences. And F. novicida Cpf1 recognizes a TTN PAMsequence. PAM sequences have been identified for a variety of RNA-guidednucleases, and a strategy for identifying novel PAM sequences has beendescribed by Shmakov et al., 2015, Molecular Cell 60, 385-397, Nov. 5,2015. It should also be noted that engineered RNA-guided nucleases canhave PAM specificities that differ from the PAM specificities ofreference molecules (for instance, in the case of an engineeredRNA-guided nuclease, the reference molecule may be the naturallyoccurring variant from which the RNA-guided nuclease is derived, or thenaturally occurring variant having the greatest amino acid sequencehomology to the engineered RNA-guided nuclease).

In addition to their PAM specificity, RNA-guided nucleases can becharacterized by their DNA cleavage activity: naturally-occurringRNA-guided nucleases typically form DSBs in target nucleic acids, butengineered variants have been produced that generate only SSBs(discussed above) Ran & Hsu, et al., Cell 154(6), 1380-1389, Sep. 12,2013 (Ran), incorporated by reference herein), or that do not cut atall.

Cas9

Crystal structures have been determined for S. pyogenes Cas9 (Jinek2014), and for S. aureus Cas9 in complex with a unimolecular guide RNAand a target DNA (Nishimasu 2014; Anders 2014; and Nishimasu 2015).

A naturally occurring Cas9 protein comprises two lobes: a recognition(REC) lobe and a nuclease (NUC) lobe; each of which comprise particularstructural and/or functional domains. The REC lobe comprises anarginine-rich bridge helix (BH) domain, and at least one REC domain(e.g. a REC1 domain and, optionally, a REC2 domain). The REC lobe doesnot share structural similarity with other known proteins, indicatingthat it is a unique functional domain. While not wishing to be bound byany theory, mutational analyses suggest specific functional roles forthe BH and REC domains: the BH domain appears to play a role in gRNA:DNArecognition, while the REC domain is thought to interact with therepeat:anti-repeat duplex of the gRNA and to mediate the formation ofthe Cas9/gRNA complex.

The NUC lobe comprises a RuvC domain, an HNH domain, and aPAM-interacting (PI) domain. The RuvC domain shares structuralsimilarity to retroviral integrase superfamily members and cleaves thenon-complementary (i.e. bottom) strand of the target nucleic acid. Itmay be formed from two or more split RuvC motifs (such as RuvC I, RuvCII, and RuvC III in S. pyogenes and S. aureus). The HNH domain,meanwhile, is structurally similar to FINN endonuclease motifs, andcleaves the complementary (i.e. top) strand of the target nucleic acid.The PI domain, as its name suggests, contributes to PAM specificity.

While certain functions of Cas9 are linked to (but not necessarily fullydetermined by) the specific domains set forth above, these and otherfunctions may be mediated or influenced by other Cas9 domains, or bymultiple domains on either lobe. For instance, in S. pyogenes Cas9, asdescribed in Nishimasu 2014, the repeat:antirepeat duplex of the gRNAfalls into a groove between the REC and NUC lobes, and nucleotides inthe duplex interact with amino acids in the BH, PI, and REC domains.Some nucleotides in the first stem loop structure also interact withamino acids in multiple domains (PI, BH and REC1), as do somenucleotides in the second and third stem loops (RuvC and PI domains).

Cpf1

The crystal structure of Acidaminococcus sp. Cpf1 in complex with crRNAand a double-stranded (ds) DNA target including a TTTN PAM sequence hasbeen solved by Yamano et al. (Cell. 2016 May 5; 165(4): 949-962(Yamano), incorporated by reference herein). Cpf1, like Cas9, has twolobes: a REC (recognition) lobe, and a NUC (nuclease) lobe. The REC lobeincludes REC1 and REC2 domains, which lack similarity to any knownprotein structures. The NUC lobe, meanwhile, includes three RuvC domains(RuvC-I, -II and -III) and a BH domain. However, in contrast to Cas9,the Cpf1 REC lobe lacks an HNH domain, and includes other domains thatalso lack similarity to known protein structures: a structurally uniquePI domain, three Wedge (WED) domains (WED-I, -II and -III), and anuclease (Nuc) domain.

While Cas9 and Cpf1 share similarities in structure and function, itshould be appreciated that certain Cpf1 activities are mediated bystructural domains that are not analogous to any Cas9 domains. Forinstance, cleavage of the complementary strand of the target DNA appearsto be mediated by the Nuc domain, which differs sequentially andspatially from the HNH domain of Cas9. Additionally, the non-targetingportion of Cpf1 gRNA (the handle) adopts a pseudoknot structure, ratherthan a stem loop structure formed by the repeat:antirepeat duplex inCas9 gRNAs.

Modifications of RNA-Guided Nucleases

The RNA-guided nucleases described above have activities and propertiesthat can be useful in a variety of applications, but the skilled artisanwill appreciate that RNA-guided nucleases can also be modified incertain instances, to alter cleavage activity, PAM specificity, or otherstructural or functional features.

Turning first to modifications that alter cleavage activity, mutationsthat reduce or eliminate the activity of domains within the NUC lobehave been described above. Exemplary mutations that may be made in theRuvC domains, in the Cas9 HNH domain, or in the Cpf1 Nuc domain aredescribed in Ran and Yamano, as well as in Cotta-Ramusino. In general,mutations that reduce or eliminate activity in one of the two nucleasedomains result in RNA-guided nucleases with nickase activity, but itshould be noted that the type of nickase activity varies depending onwhich domain is inactivated. As one example, inactivation of a RuvCdomain of a Cas9 will result in a nickase that cleaves the complementaryor top strand as shown below (where C denotes the site of cleavage):

On the other hand, inactivation of a Cas9 HNH domain results in anickase that cleaves the bottom or non-complementary strand:

Modifications of PAM specificity relative to naturally occurring Cas9reference molecules have been described by Kleinstiver et al. for bothS. pyogenes (Kleinstiver et al., Nature. 2015 Jul. 23; 523(7561):481-5(Kleinstiver I) and S. aureus (Kleinstiver et al., Nat Biotechnol. 2015December; 33(12): 1293-1298 (Klienstiver II)). Kleinstiver et al. havealso described modifications that improve the targeting fidelity of Cas9(Nature, 2016 Jan. 28; 529, 490-495 (Kleinstiver III)). Each of thesereferences is incorporated by reference herein.

RNA-guided nucleases have been split into two or more parts, asdescribed by Zetsche et al. (Nat Biotechnol. 2015 February; 33(2):139-42(Zetsche II), incorporated by reference), and by Fine et al. (Sci Rep.2015 Jul. 1; 5:10777 (Fine), incorporated by reference).

RNA-guided nucleases can be, in certain embodiments, size-optimized ortruncated, for instance via one or more deletions that reduce the sizeof the nuclease while still retaining gRNA association, target and PAMrecognition, and cleavage activities. In certain embodiments, RNA guidednucleases are bound, covalently or non-covalently, to anotherpolypeptide, nucleotide, or other structure, optionally by means of alinker. Exemplary bound nucleases and linkers are described by Guilingeret al., Nature Biotechnology 32, 577-582 (2014), which is incorporatedby reference for all purposes herein.

RNA-guided nucleases also optionally include a tag, such as, but notlimited to, a nuclear localization signal to facilitate movement ofRNA-guided nuclease protein into the nucleus. In certain embodiments,the RNA-guided nuclease can incorporate C- and/or N-terminal nuclearlocalization signals. Nuclear localization sequences are known in theart and are described in Maeder and elsewhere.

The foregoing list of modifications is intended to be exemplary innature, and the skilled artisan will appreciate, in view of the instantdisclosure, that other modifications may be possible or desirable incertain applications. For brevity, therefore, exemplary systems, methodsand compositions of the present disclosure are presented with referenceto particular RNA-guided nucleases, but it should be understood that theRNA-guided nucleases used may be modified in ways that do not altertheir operating principles. Such modifications are within the scope ofthe present disclosure.

Nucleic Acids Encoding RNA-Guided Nucleases

Nucleic acids encoding RNA-guided nucleases, e.g., Cas9, Cpf1 orfunctional fragments thereof, are provided herein. Exemplary nucleicacids encoding RNA-guided nucleases have been described previously (see,e.g., Cong 2013; Wang 2013; Mali 2013; Jinek 2012).

In some cases, a nucleic acid encoding an RNA-guided nuclease can be asynthetic nucleic acid sequence. For example, the synthetic nucleic acidmolecule can be chemically modified. In certain embodiments, an mRNAencoding an RNA-guided nuclease will have one or more (e.g., all) of thefollowing properties: it can be capped; polyadenylated; and substitutedwith 5-methylcytidine and/or pseudouridine.

Synthetic nucleic acid sequences can also be codon optimized, e.g., atleast one non-common codon or less-common codon has been replaced by acommon codon. For example, the synthetic nucleic acid can direct thesynthesis of an optimized messenger mRNA, e.g., optimized for expressionin a mammalian expression system, e.g., described herein. Examples ofcodon optimized Cas9 coding sequences are presented in Cotta-Ramusino.

In addition, or alternatively, a nucleic acid encoding an RNA-guidednuclease may comprise a nuclear localization sequence (NLS). Nuclearlocalization sequences are known in the art.

Functional Analysis of Candidate Molecules

Candidate RNA-guided nucleases, gRNAs, and complexes thereof, can beevaluated by standard methods known in the art. See, e.g.Cotta-Ramusino. The stability of RNP complexes may be evaluated bydifferential scanning fluorimetry, as described below.

Differential Scanning Fluorimetry (DSF)

The thermostability of ribonucleoprotein (RNP) complexes comprisinggRNAs and RNA-guided nucleases can be measured via DSF. The DSFtechnique measures the thermostability of a protein, which can increaseunder favorable conditions such as the addition of a binding RNAmolecule, e.g., a gRNA.

A DSF assay can be performed according to any suitable protocol, and canbe employed in any suitable setting, including without limitation (a)testing different conditions (e.g. different stoichiometric ratios ofgRNA: RNA-guided nuclease protein, different buffer solutions, etc.) toidentify optimal conditions for RNP formation; and (b) testingmodifications (e.g. chemical modifications, alterations of sequence,etc.) of an RNA-guided nuclease and/or a gRNA to identify thosemodifications that improve RNP formation or stability. One readout of aDSF assay is a shift in melting temperature of the RNP complex; arelatively high shift suggests that the RNP complex is more stable (andmay thus have greater activity or more favorable kinetics of formation,kinetics of degradation, or another functional characteristic) relativeto a reference RNP complex characterized by a lower shift. When the DSFassay is deployed as a screening tool, a threshold melting temperatureshift may be specified, so that the output is one or more RNPs having amelting temperature shift at or above the threshold. For instance, thethreshold can be 5-10° C. (e.g. 5°, 6°, 7°, 8°, 9°, 10°) or more, andthe output may be one or more RNPs characterized by a meltingtemperature shift greater than or equal to the threshold.

Two non-limiting examples of DSF assay conditions are set forth below:

To determine the best solution to form RNP complexes, a fixedconcentration (e.g. 2 μM) of Cas9 in water+10×SYPRO Orange® (LifeTechnologies cat#S-6650) is dispensed into a 384 well plate. Anequimolar amount of gRNA diluted in solutions with varied pH and salt isthen added. After incubating at room temperature for 10′ and briefcentrifugation to remove any bubbles, a Bio-Rad CFX384™ Real-Time SystemC1000 Touch™ Thermal Cycler with the Bio-Rad CFX Manager software isused to run a gradient from 20° C. to 90° C. with a 1° C. increase intemperature every 10 seconds.

The second assay consists of mixing various concentrations of gRNA withfixed concentration (e.g. 2 μM) Cas9 in optimal buffer from assay 1above and incubating (e.g. at RT for 10′) in a 384 well plate. An equalvolume of optimal buffer +10×SYPRO Orange® (Life Technologiescat#S-6650) is added and the plate sealed with Microseal® B adhesive(MSB-1001). Following brief centrifugation to remove any bubbles, aBio-Rad CFX384™ Real-Time System C1000 Touch™ Thermal Cycler with theBio-Rad CFX Manager software is used to run a gradient from 20° C. to90° C. with a 1° C. increase in temperature every 10 seconds.

Genome Editing Strategies

The genome editing systems described above are used, in variousembodiments of the present disclosure, to generate edits in (i.e. toalter) targeted regions of DNA within or obtained from a cell. Variousstrategies are described herein to generate particular edits, and thesestrategies are generally described in terms of the desired repairoutcome, the number and positioning of individual edits (e.g. SSBs orDSBs), and the target sites of such edits.

Genome editing strategies that involve the formation of SSBs or DSBs arecharacterized by repair outcomes including: (a) deletion of all or partof a targeted region; (b) insertion into or replacement of all or partof a targeted region; or (c) interruption of all or part of a targetedregion. This grouping is not intended to be limiting, or to be bindingto any particular theory or model, and is offered solely for economy ofpresentation. Skilled artisans will appreciate that the listed outcomesare not mutually exclusive and that some repairs may result in otheroutcomes. The description of a particular editing strategy or methodshould not be understood to require a particular repair outcome unlessotherwise specified.

Replacement of a targeted region generally involves the replacement ofall or part of the existing sequence within the targeted region with ahomologous sequence, for instance through gene correction or geneconversion, two repair outcomes that are mediated by HDR pathways. HDRis promoted by the use of a donor template, which can be single-strandedor double-stranded, as described in greater detail below. Single- ordouble-stranded templates can be exogenous, in which case they willpromote gene correction, or they can be endogenous (e.g. a homologoussequence within the cellular genome), to promote gene conversion.Exogenous templates can have asymmetric overhangs (i.e. the portion ofthe template that is complementary to the site of the DSB may be offsetin a 3′ or 5′ direction, rather than being centered within the donortemplate), for instance as described by Richardson et al. (NatureBiotechnology 34, 339-344 (2016), (Richardson), incorporated byreference). In instances where the template is single-stranded, it cancorrespond to either the complementary (top) or non-complementary(bottom) strand of the targeted region.

Gene conversion and gene correction are facilitated, in some cases, bythe formation of one or more nicks in or around the targeted region, asdescribed in Ran and Cotta-Ramusino. In some cases, a dual-nickasestrategy is used to form two offset SSBs that, in turn, form a singleDSB having an overhang (e.g. a 5′ overhang).

Interruption and/or deletion of all or part of a targeted sequence canbe achieved by a variety of repair outcomes. As one example, a sequencecan be deleted by simultaneously generating two or more DSBs that flanka targeted region, which is then excised when the DSBs are repaired, asis described in Maeder for the LCA10 mutation. As another example, asequence can be interrupted by a deletion generated by formation of adouble strand break with single-stranded overhangs, followed byexonucleolytic processing of the overhangs prior to repair.

One specific subset of target sequence interruptions is mediated by theformation of an indel within the targeted sequence, where the repairoutcome is typically mediated by NHEJ pathways (including Alt-NHEJ).NHEJ is referred to as an “error prone” repair pathway because of itsassociation with indel mutations. In some cases, however, a DSB isrepaired by NHEJ without alteration of the sequence around it (aso-called “perfect” or “scarless” repair); this generally requires thetwo ends of the DSB to be perfectly ligated. Indels, meanwhile, arethought to arise from enzymatic processing of free DNA ends before theyare ligated that adds and/or removes nucleotides from either or bothstrands of either or both free ends.

Because the enzymatic processing of free DSB ends may be stochastic innature, indel mutations tend to be variable, occurring along adistribution, and can be influenced by a variety of factors, includingthe specific target site, the cell type used, the genome editingstrategy used, etc. It is possible to draw limited generalizations aboutindel formation: deletions formed by repair of a single DSB are mostcommonly in the 1-50 bp range, but can reach greater than 100-200 bp.Insertions formed by repair of a single DSB tend to be shorter and ofteninclude short duplications of the sequence immediately surrounding thebreak site. However, it is possible to obtain large insertions, and inthese cases, the inserted sequence has often been traced to otherregions of the genome or to plasmid DNA present in the cells.

Indel mutations—and genome editing systems configured to produceindels—are useful for interrupting target sequences, for example, whenthe generation of a specific final sequence is not required and/or wherea frameshift mutation would be tolerated. They can also be useful insettings where particular sequences are preferred, insofar as thecertain sequences desired tend to occur preferentially from the repairof an SSB or DSB at a given site. Indel mutations are also a useful toolfor evaluating or screening the activity of particular genome editingsystems and their components. In these and other settings, indels can becharacterized by (a) their relative and absolute frequencies in thegenomes of cells contacted with genome editing systems and (b) thedistribution of numerical differences relative to the unedited sequence,e.g. ±1, ±2, ±3, etc. As one example, in a lead-finding setting,multiple gRNAs can be screened to identify those gRNAs that mostefficiently drive cutting at a target site based on an indel readoutunder controlled conditions. Guides that produce indels at or above athreshold frequency, or that produce a particular distribution ofindels, can be selected for further study and development. Indelfrequency and distribution can also be useful as a readout forevaluating different genome editing system implementations orformulations and delivery methods, for instance by keeping the gRNAconstant and varying certain other reaction conditions or deliverymethods.

Multiplex Strategies

While exemplary strategies discussed above have focused on repairoutcomes mediated by single DSBs, genome editing systems according tothis disclosure may also be employed to generate two or more DSBs,either in the same locus or in different loci. Strategies for editingthat involve the formation of multiple DSBs, or SSBs, are described in,for instance, Cotta-Ramusino.

Donor Template Design

Donor template design is described in detail in the literature, forinstance in Cotta-Ramusino. DNA oligomer donor templates(oligodeoxynucleotides or ODNs), which can be single-stranded (ssODNs)or double-stranded (dsODNs), can be used to facilitate HDR-based repairof DSBs, and are particularly useful for introducing alterations into atarget DNA sequence, inserting a new sequence into the target sequence,or replacing the target sequence altogether.

Whether single-stranded or double-stranded, donor templates generallyinclude regions that are homologous to regions of DNA within or near(e.g. flanking or adjoining) a target sequence to be cleaved. Thesehomologous regions are referred to here as “homology arms,” and areillustrated schematically below:

-   -   [5′ homology arm]-[replacement sequence]-[3′ homology arm].

The homology arms can have any suitable length (including 0 nucleotidesif only one homology arm is used), and 3′ and 5′ homology arms can havethe same length, or can differ in length. The selection of appropriatehomology arm lengths can be influenced by a variety of factors, such asthe desire to avoid homologies or microhomologies with certain sequencessuch as Alu repeats or other very common elements. For example, a 5′homology arm can be shortened to avoid a sequence repeat element. Inother embodiments, a 3′ homology arm can be shortened to avoid asequence repeat element. In some embodiments, both the 5′ and the 3′homology arms can be shortened to avoid including certain sequencerepeat elements. In addition, some homology arm designs can improve theefficiency of editing or increase the frequency of a desired repairoutcome. For example, Richardson et al. Nature Biotechnology 34, 339-344(2016) (Richardson), which is incorporated by reference, found that therelative asymmetry of 3′ and 5′ homology arms of single-stranded donortemplates influenced repair rates and/or outcomes.

Replacement sequences in donor templates have been described elsewhere,including in Cotta-Ramusino et al. A replacement sequence can be anysuitable length (including zero nucleotides, where the desired repairoutcome is a deletion), and typically includes one, two, three or moresequence modifications relative to the naturally-occurring sequencewithin a cell in which editing is desired. One common sequencemodification involves the alteration of the naturally-occurring sequenceto repair a mutation that is related to a disease or condition of whichtreatment is desired. Another common sequence modification involves thealteration of one or more sequences that are complementary to, or codefor, the PAM sequence of the RNA-guided nuclease or the targeting domainof the gRNA(s) being used to generate an SSB or DSB, to reduce oreliminate repeated cleavage of the target site after the replacementsequence has been incorporated into the target site.

Where a linear ssODN is used, it can be configured to (i) anneal to thenicked strand of the target nucleic acid, (ii) anneal to the intactstrand of the target nucleic acid, (iii) anneal to the plus strand ofthe target nucleic acid, and/or (iv) anneal to the minus strand of thetarget nucleic acid. An ssODN may have any suitable length, e.g., about,or no more than 150-200 nucleotides (e.g., 150, 160, 170, 180, 190, or200 nucleotides).

It should be noted that a template nucleic acid can also be a nucleicacid vector, such as a viral genome or circular double-stranded DNA,e.g., a plasmid. Nucleic acid vectors comprising donor templates caninclude other coding or non-coding elements. For example, a templatenucleic acid can be delivered as part of a viral genome (e.g. in an AAVor lentiviral genome) that includes certain genomic backbone elements(e.g. inverted terminal repeats, in the case of an AAV genome) andoptionally includes additional sequences coding for a gRNA and/or anRNA-guided nuclease. In certain embodiments, the donor template can beadjacent to, or flanked by, target sites recognized by one or moregRNAs, to facilitate the formation of free DSBs on one or both ends ofthe donor template that can participate in repair of corresponding SSBsor DSBs formed in cellular DNA using the same gRNAs. Exemplary nucleicacid vectors suitable for use as donor templates are described inCotta-Ramusino.

Whatever format is used, a template nucleic acid can be designed toavoid undesirable sequences. In certain embodiments, one or bothhomology arms can be shortened to avoid overlap with certain sequencerepeat elements, e.g., Alu repeats, LINE elements, etc.

Target Cells

Genome editing systems according to this disclosure can be used tomanipulate or alter a cell, e.g., to edit or alter a target nucleicacid. The manipulating can occur, in various embodiments, in vivo or exvivo.

A variety of cell types can be manipulated or altered according to theembodiments of this disclosure, and in some cases, such as in vivoapplications, a plurality of cell types are altered or manipulated, forexample by delivering genome editing systems according to thisdisclosure to a plurality of cell types. In other cases, however, it maybe desirable to limit manipulation or alteration to a particular celltype or types. For instance, it can be desirable in some instances toedit a cell with limited differentiation potential or a terminallydifferentiated cell, such as a photoreceptor cell in the case of Maeder,in which modification of a genotype is expected to result in a change incell phenotype. In other cases, however, it may be desirable to edit aless differentiated, multipotent or pluripotent, stem or progenitorcell. By way of example, the cell may be an embryonic stem cell, inducedpluripotent stem cell (iPSC), hematopoietic stem/progenitor cell (HSPC),or other stem or progenitor cell type that differentiates into a celltype of relevance to a given application or indication.

As a corollary, the cell being altered or manipulated is, variously, adividing cell or a non-dividing cell, depending on the cell type(s)being targeted and/or the desired editing outcome.

When cells are manipulated or altered ex vivo, the cells can be used(e.g. administered to a subject) immediately, or they can be maintainedor stored for later use. Those of skill in the art will appreciate thatcells can be maintained in culture or stored (e.g. frozen in liquidnitrogen) using any suitable method known in the art.

Implementation of Genome Editing Systems: Delivery, Formulations, andRoutes of Administration

As discussed above, the genome editing systems of this disclosure can beimplemented in any suitable manner, meaning that the components of suchsystems, including without limitation the RNA-guided nuclease, gRNA, andoptional donor template nucleic acid, can be delivered, formulated, oradministered in any suitable form or combination of forms that resultsin the transduction, expression or introduction of a genome editingsystem and/or causes a desired repair outcome in a cell, tissue orsubject. Tables 6 and 7 set forth several, non-limiting examples ofgenome editing system implementations. Those of skill in the art willappreciate, however, that these listings are not comprehensive, and thatother implementations are possible. With reference to Table 6 inparticular, the table lists several exemplary implementations of agenome editing system comprising a single gRNA and an optional donortemplate. However, genome editing systems according to this disclosurecan incorporate multiple gRNAs, multiple RNA-guided nucleases, and othercomponents such as proteins, and a variety of implementations will beevident to the skilled artisan based on the principles illustrated inthe table. In the table, [N/A] indicates that the genome editing systemdoes not include the indicated component.

Table 7 summarizes various delivery methods for the components of genomeediting systems, as described herein. Again, the listing is intended tobe exemplary rather than limiting.

TABLE 7 Delivery into Non- Type of Dividing Duration of Genome MoleculeDelivery Vector/Mode Cells Expression Integration Delivered Physical(e.g., electroporation, YES Transient NO Nucleic Acids particle gun,Calcium Phosphate and Proteins transfection, cell compression orsqueezing) Viral Retrovirus NO Stable YES RNA Lentivirus YES StableYES/NO with RNA modifications Adenovirus YES Transient NO DNA Adeno- YESStable NO DNA Associated Virus (AAV) Vaccinia Virus YES Very NO DNATransient Herpes Simplex YES Stable NO DNA Virus Non-Viral Cationic YESTransient Depends on Nucleic Acids Liposomes what is and Proteinsdelivered Polymeric YES Transient Depends on Nucleic Acids Nanoparticleswhat is and Proteins delivered Biological Attenuated YES Transient NONucleic Acids Non-Viral Bacteria Delivery Engineered YES Transient NONucleic Acids Vehicles Bacteriophages Mammalian YES Transient NO NucleicAcids Virus-like Particles Biological YES Transient NO Nucleic Acidsliposomes: Erythrocyte Ghosts and Exosomes

Nucleic Acid-Based Delivery of Genome Editing Systems

Nucleic acids encoding the various elements of a genome editing systemaccording to the present disclosure can be administered to subjects ordelivered into cells by art-known methods or as described herein. Forexample, RNA-guided nuclease-encoding and/or gRNA-encoding DNA, as wellas donor template nucleic acids can be delivered by, e.g., vectors(e.g., viral or non-viral vectors), non-vector based methods (e.g.,using naked DNA or DNA complexes), or a combination thereof.

Nucleic acids encoding genome editing systems or components thereof canbe delivered directly to cells as naked DNA or RNA, for instance bymeans of transfection or electroporation, or can be conjugated tomolecules (e.g., N-acetylgalactosamine) promoting uptake by the targetcells (e.g., erythrocytes, HSCs). Nucleic acid vectors, such as thevectors summarized in Table 7, can also be used.

Nucleic acid vectors can comprise one or more sequences encoding genomeediting system components, such as an RNA-guided nuclease, a gRNA and/ora donor template. A vector can also comprise a sequence encoding asignal peptide (e.g., for nuclear localization, nucleolar localization,or mitochondrial localization), associated with (e.g., inserted into orfused to) a sequence coding for a protein. As one example, a nucleicacid vectors can include a Cas9 coding sequence that includes one ormore nuclear localization sequences (e.g., a nuclear localizationsequence from SV40).

The nucleic acid vector can also include any suitable number ofregulatory/control elements, e.g., promoters, enhancers, introns,polyadenylation signals, Kozak consensus sequences, or internal ribosomeentry sites (IRES). These elements are well known in the art, and aredescribed in Cotta-Ramusino.

Nucleic acid vectors according to this disclosure include recombinantviral vectors. Exemplary viral vectors are set forth in Table 7, andadditional suitable viral vectors and their use and production aredescribed in Cotta-Ramusino. Other viral vectors known in the art canalso be used. In addition, viral particles can be used to deliver genomeediting system components in nucleic acid and/or peptide form. Forexample, “empty” viral particles can be assembled to contain anysuitable cargo. Viral vectors and viral particles can also be engineeredto incorporate targeting ligands to alter target tissue specificity.

In addition to viral vectors, non-viral vectors can be used to delivernucleic acids encoding genome editing systems according to the presentdisclosure. One important category of non-viral nucleic acid vectors arenanoparticles, which can be organic or inorganic. Nanoparticles are wellknown in the art, and are summarized in Cotta-Ramusino. Any suitablenanoparticle design can be used to deliver genome editing systemcomponents or nucleic acids encoding such components. For instance,organic (e.g. lipid and/or polymer) nanoparticles can be suitable foruse as delivery vehicles in certain embodiments of this disclosure.Exemplary lipids for use in nanoparticle formulations, and/or genetransfer are shown in Table 8, and Table 9 lists exemplary polymers foruse in gene transfer and/or nanoparticle formulations.

TABLE 8 Lipids Used for Gene Transfer Lipid Abbreviation Feature1,2-Dioleoyl-sn-glycero-3-phosphatidylcholine DOPC Helper1,2-Dioleoyl-sn-glycero-3-phosphatidylethanolamine DOPE HelperCholesterol Helper N-[1-(2,3-Dioleyloxy)propyl]N,N,N-trimethylammoniumchloride DOTMA Cationic 1,2-Dioleoyloxy-3-trimethylammonium-propaneDOTAP Cationic Dioctadecylamidoglycylspermine DOGS CationicN-(3-Aminopropyl)-N,N-dimethyl-2,3-bis(dodecyloxy)-1- GAP-DLRIE Cationicpropanaminium bromide Cetyltrimethylammonium bromide CTAB Cationic6-Lauroxyhexyl ornithinate LHON Cationic1-(2,3-Dioleoyloxypropyl)-2,4,6-trimethylpyridinium 2Oc Cationic2,3-Dioleyloxy-N-[2(sperminecarboxamido-ethyl]-N,N-dimethyl-1- DOSPACationic propanaminium trifluoroacetate1,2-Dioleyl-3-trimethylammonium-propane DOPA CationicN-(2-Hydroxyethyl)-N,N-dimethyl-2,3-bis(tetradecyloxy)-1- MDRIE Cationicpropanaminium bromide Dimyristooxypropyl dimethyl hydroxyethyl ammoniumbromide DMRI Cationic3β-[N-(N′,N′-Dimethylaminoethane)-carbamoyl]cholesterol DC-Chol CationicBis-guanidium-tren-cholesterol BGTC Cationic1,3-Diodeoxy-2-(6-carboxy-spermyl)-propylamide DOSPER CationicDimethyloctadecylammonium bromide DDAB CationicDioctadecylamidoglicylspermidin DSL Cationicrac-[(2,3-Dioctadecyloxypropyl)(2-hydroxyethyl)]-dimethylammonium CLIP-1Cationic chloride rac-[2(2,3-Dihexadecyloxypropyl- CLIP-6 Cationicoxymethyloxy)ethyl]trimethylammonium bromideEthyldimyristoylphosphatidylcholine EDMPC Cationic1,2-Distearyloxy-N,N-dimethyl-3-aminopropane DSDMA Cationic1,2-Dimyristoyl-trimethylammonium propane DMTAP CationicO,O′-Dimyristyl-N-lysyl aspartate DMKE Cationic1,2-Distearoyl-sn-glycero-3-ethylphosphocholine DSEPC CationicN-Palmitoyl D-erythro-sphingosyl carbamoyl-spermine CCS CationicN-t-Butyl-N0-tetradecyl-3-tetradecylaminopropionamidine diC14-amidineCationic Octadecenolyoxy[ethyl-2-heptadecenyl-3 hydroxyethyl]imidazolinium DOTIM Cationic chlorideN1-Cholesteryloxycarbonyl-3,7-diazanonane-1,9-diamine CDAN Cationic2-(3-[Bis(3-amino-propyl)-amino]propylamino)-N- RPR209120 Cationicditetradecylcarbamoylme-ethyl-acetamide1,2-dilinoleyloxy-3-dimethylaminopropane DLinDMA Cationic2,2-dilinoleyl-4-dimethylaminoethyl-[1,3]-dioxolane DLin-KC2-DMACationic dilinoleyl-methyl-4-dimethylaminobutyrate DLin-MC3-DMA Cationic

TABLE 9 Polymers Used for Gene Transfer Polymer AbbreviationPoly(ethylene)glycol PEG Polyethylenimine PEIDithiobis(succinimidylpropionate) DSPDimethyl-3,3′-dithiobispropionimidate DTBP Poly(ethylene imine)biscarbamate PEIC Poly(L-lysine) PLL Histidine modified PLLPoly(N-vinylpyrrolidone) PVP Poly(propylenimine) PPI Poly(amidoamine)PAMAM Poly(amido ethylenimine) SS-PAEI Triethylenetetramine TETAPoly(β-aminoester) Poly(4-hydroxy-L-proline ester) PHP Poly(allylamine)Poly(α-[4-aminobutyl]-L-glycolic acid) PAGA Poly(D,L-lactic-co-glycolicacid) PLGA Poly(N-ethyl-4-vinylpyridinium bromide) Poly(phosphazene)sPPZ Poly(phosphoester)s PPE Poly(phosphoramidate)s PPAPoly(N-2-hydroxypropylmethacrylamide) pHPMA Poly (2-(dimethylamino)ethylmethacrylate) pDMAEMA Poly(2-aminoethyl propylene phosphate) PPE-EAChitosan Galactosylated chitosan N-Dodacylated chitosan Histone CollagenDextran-spermine D-SPM

Non-viral vectors optionally include targeting modifications to improveuptake and/or selectively target certain cell types. These targetingmodifications can include e.g., cell specific antigens, monoclonalantibodies, single chain antibodies, aptamers, polymers, sugars (e.g.,N-acetylgalactosamine (GalNAc)), and cell penetrating peptides. Suchvectors also optionally use fusogenic and endosome-destabilizingpeptides/polymers, undergo acid-triggered conformational changes (e.g.,to accelerate endosomal escape of the cargo), and/or incorporate astimuli-cleavable polymer, e.g., for release in a cellular compartment.For example, disulfide-based cationic polymers that are cleaved in thereducing cellular environment can be used.

In certain embodiments, one or more nucleic acid molecules (e.g., DNAmolecules) other than the components of a genome editing system, e.g.,the RNA-guided nuclease component and/or the gRNA component describedherein, are delivered. In certain embodiments, the nucleic acid moleculeis delivered at the same time as one or more of the components of thegenome editing system. In certain embodiments, the nucleic acid moleculeis delivered before or after (e.g., less than about 30 minutes, 1 hour,2 hours, 3 hours, 6 hours, 9 hours, 12 hours, 1 day, 2 days, 3 days, 1week, 2 weeks, or 4 weeks) one or more of the components of the genomeediting system are delivered. In certain embodiments, the nucleic acidmolecule is delivered by a different means than one or more of thecomponents of the genome editing system, e.g., the RNA-guided nucleasecomponent and/or the gRNA component, are delivered. The nucleic acidmolecule can be delivered by any of the delivery methods describedherein. For example, the nucleic acid molecule can be delivered by aviral vector, e.g., an integration-deficient lentivirus, and theRNA-guided nuclease molecule component and/or the gRNA component can bedelivered by electroporation, e.g., such that the toxicity caused bynucleic acids (e.g., DNAs) can be reduced. In certain embodiments, thenucleic acid molecule encodes a therapeutic protein, e.g., a proteindescribed herein. In certain embodiments, the nucleic acid moleculeencodes an RNA molecule, e.g., an RNA molecule described herein.

Delivery of RNPs and/or RNA Encoding Genome Editing System Components

RNPs (complexes of gRNAs and RNA-guided nucleases, i.e.,ribonucleoprotein complexes) and/or RNAs encoding RNA-guided nucleasesand/or gRNAs, can be delivered into cells or administered to subjects byart-known methods, some of which are described in Cotta-Ramusino. Invitro, RNA-guided nuclease-encoding and/or gRNA-encoding RNA can bedelivered, e.g., by microinjection, electroporation, transient cellcompression or squeezing (see, e.g., Lee 2012). Lipid-mediatedtransfection, peptide-mediated delivery, GalNAc- or otherconjugate-mediated delivery, and combinations thereof, can also be usedfor delivery in vitro and in vivo.

In vitro, delivery via electroporation comprises mixing the cells withthe RNA encoding RNA-guided nucleases and/or gRNAs, with or withoutdonor template nucleic acid molecules, in a cartridge, chamber orcuvette and applying one or more electrical impulses of defined durationand amplitude. Systems and protocols for electroporation are known inthe art, and any suitable electroporation tool and/or protocol can beused in connection with the various embodiments of this disclosure.

Route of Administration

Genome editing systems, or cells altered or manipulated using suchsystems, can be administered to subjects by any suitable mode or route,whether local or systemic. Systemic modes of administration include oraland parenteral routes. Parenteral routes include, by way of example,intravenous, intramarrow, intrarterial, intramuscular, intradermal,subcutaneous, intranasal, and intraperitoneal routes. Componentsadministered systemically can be modified or formulated to target, e.g.,HSCs, hematopoietic stem/progenitor cells, or erythroid progenitors orprecursor cells.

Local modes of administration include, by way of example, intramarrowinjection into the trabecular bone or intrafemoral injection into themarrow space, and infusion into the portal vein. In certain embodiments,significantly smaller amounts of the components (compared with systemicapproaches) can exert an effect when administered locally (for example,directly into the bone marrow) compared to when administeredsystemically (for example, intravenously). Local modes of administrationcan reduce or eliminate the incidence of potentially toxic side effectsthat may occur when therapeutically effective amounts of a component areadministered systemically.

Administration can be provided as a periodic bolus (for example,intravenously) or as continuous infusion from an internal reservoir orfrom an external reservoir (for example, from an intravenous bag orimplantable pump). Components can be administered locally, for example,by continuous release from a sustained release drug delivery device.

In addition, components can be formulated to permit release over aprolonged period of time. A release system can include a matrix of abiodegradable material or a material which releases the incorporatedcomponents by diffusion. The components can be homogeneously orheterogeneously distributed within the release system. A variety ofrelease systems can be useful, however, the choice of the appropriatesystem will depend upon rate of release required by a particularapplication. Both non-degradable and degradable release systems can beused. Suitable release systems include polymers and polymeric matrices,non-polymeric matrices, or inorganic and organic excipients and diluentssuch as, but not limited to, calcium carbonate and sugar (for example,trehalose). Release systems may be natural or synthetic. However,synthetic release systems are preferred because generally they are morereliable, more reproducible and produce more defined release profiles.The release system material can be selected so that components havingdifferent molecular weights are released by diffusion through ordegradation of the material.

Representative synthetic, biodegradable polymers include, for example:polyamides such as poly(amino acids) and poly(peptides); polyesters suchas poly(lactic acid), poly(glycolic acid), poly(lactic-co-glycolicacid), and poly(caprolactone); poly(anhydrides); polyorthoesters;polycarbonates; and chemical derivatives thereof (substitutions,additions of chemical groups, for example, alkyl, alkylene,hydroxylations, oxidations, and other modifications routinely made bythose skilled in the art), copolymers and mixtures thereof.Representative synthetic, non-degradable polymers include, for example:polyethers such as poly(ethylene oxide), poly(ethylene glycol), andpoly(tetramethylene oxide); vinyl polymers-polyacrylates andpolymethacrylates such as methyl, ethyl, other alkyl, hydroxyethylmethacrylate, acrylic and methacrylic acids, and others such aspoly(vinyl alcohol), poly(vinyl pyrolidone), and poly(vinyl acetate);poly(urethanes); cellulose and its derivatives such as alkyl,hydroxyalkyl, ethers, esters, nitrocellulose, and various celluloseacetates; polysiloxanes; and any chemical derivatives thereof(substitutions, additions of chemical groups, for example, alkyl,alkylene, hydroxylations, oxidations, and other modifications routinelymade by those skilled in the art), copolymers and mixtures thereof.

Poly(lactide-co-glycolide) microsphere can also be used. Typically themicrospheres are composed of a polymer of lactic acid and glycolic acid,which are structured to form hollow spheres. The spheres can beapproximately 15-30 microns in diameter and can be loaded withcomponents described herein.

Multi-modal or Differential Delivery of Components

Skilled artisans will appreciate, in view of the instant disclosure,that different components of genome editing systems disclosed herein canbe delivered together or separately and simultaneously ornonsimultaneously. Separate and/or asynchronous delivery of genomeediting system components can be particularly desirable to providetemporal or spatial control over the function of genome editing systemsand to limit certain effects caused by their activity.

Different or differential modes as used herein refer to modes ofdelivery that confer different pharmacodynamic or pharmacokineticproperties on the subject component molecule, e.g., a RNA-guidednuclease molecule, gRNA, template nucleic acid, or payload. For example,the modes of delivery can result in different tissue distribution,different half-life, or different temporal distribution, e.g., in aselected compartment, tissue, or organ.

Some modes of delivery, e.g., delivery by a nucleic acid vector thatpersists in a cell, or in progeny of a cell, e.g., by autonomousreplication or insertion into cellular nucleic acid, result in morepersistent expression of and presence of a component. Examples includeviral, e.g., AAV or lentivirus, delivery.

By way of example, the components of a genome editing system, e.g., aRNA-guided nuclease and a gRNA, can be delivered by modes that differ interms of resulting half-life or persistent of the delivered componentthe body, or in a particular compartment, tissue or organ. In certainembodiments, a gRNA can be delivered by such modes. The RNA-guidednuclease molecule component can be delivered by a mode which results inless persistence or less exposure to the body or a particularcompartment or tissue or organ.

More generally, in certain embodiments, a first mode of delivery is usedto deliver a first component and a second mode of delivery is used todeliver a second component. The first mode of delivery confers a firstpharmacodynamic or pharmacokinetic property. The first pharmacodynamicproperty can be, e.g., distribution, persistence, or exposure, of thecomponent, or of a nucleic acid that encodes the component, in the body,a compartment, tissue or organ. The second mode of delivery confers asecond pharmacodynamic or pharmacokinetic property. The secondpharmacodynamic property can be, e.g., distribution, persistence, orexposure, of the component, or of a nucleic acid that encodes thecomponent, in the body, a compartment, tissue or organ.

In certain embodiments, the first pharmacodynamic or pharmacokineticproperty, e.g., distribution, persistence or exposure, is more limitedthan the second pharmacodynamic or pharmacokinetic property.

In certain embodiments, the first mode of delivery is selected tooptimize, e.g., minimize, a pharmacodynamic or pharmacokinetic property,e.g., distribution, persistence or exposure.

In certain embodiments, the second mode of delivery is selected tooptimize, e.g., maximize, a pharmacodynamic or pharmacokinetic property,e.g., distribution, persistence or exposure.

In certain embodiments, the first mode of delivery comprises the use ofa relatively persistent element, e.g., a nucleic acid, e.g., a plasmidor viral vector, e.g., an AAV or lentivirus. As such vectors arerelatively persistent product transcribed from them would be relativelypersistent.

In certain embodiments, the second mode of delivery comprises arelatively transient element, e.g., an RNA or protein.

In certain embodiments, the first component comprises gRNA, and thedelivery mode is relatively persistent, e.g., the gRNA is transcribedfrom a plasmid or viral vector, e.g., an AAV or lentivirus.Transcription of these genes would be of little physiologicalconsequence because the genes do not encode for a protein product, andthe gRNAs are incapable of acting in isolation. The second component, aRNA-guided nuclease molecule, is delivered in a transient manner, forexample as mRNA or as protein, ensuring that the full RNA-guidednuclease molecule/gRNA complex is only present and active for a shortperiod of time.

Furthermore, the components can be delivered in different molecular formor with different delivery vectors that complement one another toenhance safety and tissue specificity.

Use of differential delivery modes can enhance performance, safety,and/or efficacy, e.g., the likelihood of an eventual off-targetmodification can be reduced. Delivery of immunogenic components, e.g.,Cas9 molecules, by less persistent modes can reduce immunogenicity, aspeptides from the bacterially-derived Cas enzyme are displayed on thesurface of the cell by MHC molecules. A two-part delivery system canalleviate these drawbacks.

Differential delivery modes can be used to deliver components todifferent, but overlapping target regions. The formation active complexis minimized outside the overlap of the target regions. Thus, in certainembodiments, a first component, e.g., a gRNA is delivered by a firstdelivery mode that results in a first spatial, e.g., tissue,distribution. A second component, e.g., a RNA-guided nuclease moleculeis delivered by a second delivery mode that results in a second spatial,e.g., tissue, distribution. In certain embodiments, the first modecomprises a first element selected from a liposome, nanoparticle, e.g.,polymeric nanoparticle, and a nucleic acid, e.g., viral vector. Thesecond mode comprises a second element selected from the group. Incertain embodiments, the first mode of delivery comprises a firsttargeting element, e.g., a cell specific receptor or an antibody, andthe second mode of delivery does not include that element. In certainembodiments, the second mode of delivery comprises a second targetingelement, e.g., a second cell specific receptor or second antibody.

When the RNA-guided nuclease molecule is delivered in a virus deliveryvector, a liposome, or polymeric nanoparticle, there is the potentialfor delivery to and therapeutic activity in multiple tissues, when itmay be desirable to only target a single tissue. A two-part deliverysystem can resolve this challenge and enhance tissue specificity. If thegRNA and the RNA-guided nuclease molecule are packaged in separateddelivery vehicles with distinct but overlapping tissue tropism, thefully functional complex is only be formed in the tissue that istargeted by both vectors.

EXAMPLES

The following Examples are merely illustrative and are not intended tolimit the scope or content of the invention in any way.

Example 1 Self-Inactivating Design Embeds Target Sites in Vector

An AAV vector system is engineered such that it containsself-inactivating, universally applicable, tunable modules. Thesemodules include the already-targeted endogenous cellular sequence,obviating the need for any additional gRNAs. In addition, these modulescan be tuned based on positions within the viral genome, choice of gRNA,or PAM sequence.

The self-inactivating design contains DNA sequences that are identicalor nearly identical to that of the endogenous target locus. FIG. 1A is adiagram illustrating a SaCas9 (S. aureus Cas9)-gRNA complex targets bothan endogenous cellular target and a nucleic acid encoding the SaCas9 ina viral vector.

Target sequences in the AAV are variably positioned, at either a site inthe viral backbone or one of four regions in the SaCas9 codingsequences, and contain either canonical or suboptimal PAMs. FIG. 1B is acartoon diagram depicting a 2-vector system in which engineered SaCas9and gRNAS are encoded on separate viral genomes. Three types ofexemplary sites in an AAV genome into which heterologous cellularsequences can be engineered are marked by arrows. In type (a), thecellular sequence is inserted at a site in the AAV backbone; in type(b), the cellular sequence is inserted at one of four regions (AC1, AC2,AC3, or N-terminal (NT)) in the SaCas9 coding sequence. In certain AAVvectors, the cellular sequences can be inserted at both type (a) andtype (b) sites. SaCas9 and gRNAs can also be engineered into asingle-vector system.

Example 2 Target Sites in SaCas9 do not Disrupt SaCas9 Nuclease Activity

This example provides systems and methods of engineering of targetssites in SaCas9 coding sequences that do not disrupt SaCas9 nucleaseactivity. Various plasmids were constructed, with different target sitesat four different positions (NT, AC1, AC2, or AC3) in the SaCas9 codingsequence. FIG. 4A is a cartoon diagram depicting exemplary constructswith target sites at the four different positions in the SaCas9 codingsequence, as well as a human VEGFA-3 gRNA expression plasmid. The targetsites were from mCEP290 (guides 7, 9), hCEP290 (guides 64, 323, KKH) andSERPINA1 (guides 333 and 776).

Self-inactivating or control Cas9 plasmids were transfected into HEK293cells along with the gRNA expression plasmid targeting VEFGA site 3.mCherry was expressed through a separate promoter and was used tonormalize the transfected amount of plasmid. GFP was expressed from thesame transcript as SaCas9 and was used to measure the potentialdifferences between transcription and translation rates. FIG. 4B showsthat self-inactivating SaCas9 mutants exhibited similar expression levelcompared to control SaCas9 (WT) in HEK293 cells. GFP expression inself-inactivating SaCas9 constructs correlated with that of controlSaCas9 constructs (WT), indicating unhindered transcription andtranslation of the self-inactivating SaCas9.

Wild-type control and engineered self-inactivating SaCas9 proteinsexhibited similar levels of nuclease activity as shown in FIGS. 4C-4E.Self-inactivating SaCas9 constructs having specific target sequencesinserted at specific target sites are indicated in each figure. Targetsites AC1, AC2, AC3, and NT are in the coding sequence as depicted inFIGS. 1B and 2. Target sequences m7, m9, a3, a7, 64-1, 64-2, 323-1,323-2, KKH-1, and KKH-2 refer to sequences in genes mouse CEP290 (guidesm7 and m9), human A1ATSERPINA1 (guides a3 and a7), and human CEP290(guides 64-1, 64-2, 323-1, 323-2, KKH-1, and KKH-2), which are shown inTable 10 below. Control (labeled as “Standard”) and self-inactivatingSaCas9 nuclease activity was measured by a T7E1 assay. The x-axis showsthe amount of plasmid transfected into HEK293 cells, and the y-axisshows the % indels in VEGFA-3 as determined by the T7E1 assay.

TABLE 10 Target name Target sequence m7AAGCTGCGTGAGACATGTGTTT [SEQ ID NO: 15] m9AGCTATCTGTAGCATGCTGA [SEQ ID NO: 16] a3AAGGCTGTAGCGATGCTCACTG [SEQ ID NO: 17] a7GTGTGCCAGCTGGCGGTATAGG [SEQ ID NO: 18] 64-1 andGTCAAAAGCTACCGGTTACCTG [SEQ ID NO: 19] 64-2 323-1 andGTTCTGTCCTCAGTAAAAGGTA [SEQ ID NO: 20] 323-2 KKH-1 andCAATAGGGATAGGTATGAGATACT [SEQ ID NO: 21] KKH-2

Example 3 Self-Inactivating AAVs Maintain Efficacy at Target GFPPlasmids While Self-Inactivating in HEK293 Cells

This example provides in vitro data demonstrating the feasibility ofattaining both robust target modification and self-targeting the pool ofAAV DNA at its source.

HEK293 cells were seeded in 24-well plates and transfected with 500ng/well of GFP expression plasmids containing gRNA target sites embeddedin the 5′ end of the GFP coding sequences. The HEK293 cells weretransduced the next day with a mixture of gRNA AAV targeting GFP, andeither wild-type or self-targeting SaCas9 AAV (as shown in FIG. 1B) at atotal dose of 200,000 vg/cell. Two days later, cells were analyzed byfluorescence-activated cell sorting (FACS) to determine knockdown of GFPexpression. A schematic of the experimental design is shown in FIG. 5A.FIG. 5B shows GFP expression levels in HEK293 cells with or withoutwild-type or engineered SaCas9 proteins. Control: no SaCas9 protein; WT:wild-type SaCas9 protein; BB (sub): engineered SaCas9 with target siteinserted in the AAV backbone with suboptimal PAM sequence NNGRRA orNNGRRV; BB: engineered SaCas9 with target site inserted in the AAVbackbone with canonical PAM sequence; AC1: engineered SaCas9 with targetsite inserted at the AC1 site of the SaCas9 coding sequence; BB/AC1:engineered SaCas9 with target site inserted both in the AAV backbone andat the AC1 site of the SaCas9 coding sequence. Two different gRNAconstructs (mCEP-7 and mCEP-9) were tested individually withself-inactivating SaCas9 proteins. As shown in FIG. 5B, lower leftpanel, the control SaCas9 construct (WT) and the self-inactivatingSaCas9 constructs exhibited similar capacities in knocking down GFPexpression.

Protein was also harvested and SaCas9 level was quantified by analphaLISA assay. FIG. 5B, lower right panel shows Cas9 protein levels inHEK293 cells transduced with wild-type or self-inactivating SaCas9constructs. All cells transduced with self-inactivating SaCas9constructs exhibited reduced levels of SaCas9 protein, Engineered SaCas9constructs with target site inserted at the AC1 site of SaCas9 codingsequence exhibited improved efficacy of self-inactivation compared toSaCas9 constructs with target site inserted in the AAV backbone alone.In addition, gRNA mCEP-9 exhibited stronger self-inactivating capacitythan gRNA mCEP-7 .

Example 4 Self-Inactivating AAVs Maintain Efficacy at Target Locus WhileSelf-Inactivating in Retinal Explants

This example provides tissue explant data demonstrating the feasibilityof attaining both robust target modification and self-targeting the poolof AAV DNA at its source.

Retinal explants were extracted from BL6 mice and cultured in 24-wellplates. The explants were transduced with a mixture of gRNA AAV andeither wild-type or self-targeting SaCas9 AAV (as shown in FIG. 1B) at atotal dose of 1E11 vg/retina. At day 14 post extraction, both DNA andRNA were harvested from the explants. The endogenous target locus(mCEP290) was amplified from extracted DNA by PCR, cloned into TOPOvector, and sequenced. Control (WT) or self-inactivating SaCas9constructs exhibited similar gene editing rate at the endogenous targetlocus in mouse retinal explants as shown in FIG. 6A.

In addition, cDNA was generated from the extracted RNA. SaCas9 sequencewas amplified by PCR, cloned into TOPO vector, and sequenced. The %indel rates in SaCas9 cDNA are shown in FIG. 6B.

Example 5 Self-Inactivating AAVs Successfully Modified Target Loci WhileSelf-Inactivating In Vivo

This example provides in vivo data demonstrating the feasibility ofattaining both efficient target modification and self-targeting the poolof AAV DNA at its source. AAVs with SaCas9 and gRNAs targeting mCEP290were injected sub-retinally into C57BL/6J mice, and retinas wereharvested 6 weeks later for DNA and cDNA sequencing.

A mixture of gRNA AAV and either wild-type control or self-targetingSaCas9 AAV (as shown in FIG. 1B) at a total dose of 1.16×10¹⁰ AAV pereye were transduced. At 6 weeks post transduction, both DNA and RNA wereharvested from the animal tissue. The endogenous target locus wasamplified from extracted DNA by PCR and sequenced with Next GenerationSequencing methods on a Miseq machine. Self-inactivating SaCas9constructs exhibited efficient gene editing rates compared to thenegative control as shown in FIG. 7A, though the gene editing rates ofSaCas9 constructs having targeting sites within Cas9 coding sequence (ACand BB/AC) were relatively lower compared to the wild-type control.

In addition, cDNA was generated from the extracted RNA. SaCas9 sequencewas amplified by PCR, cloned into TOPO vector, and sequenced. The foldchange of specific transcripts of the self-inactivating SaCas9constructs compared to the wild-type SaCas9 construct are shown in FIG.7B. Transcripts containing SaCas9 coding sequence were significantlyreduced in tissues transduced with AC-m9-WT PAM construct(self-inactivating SaCas9 having target site inserted at the AC1 site ofthe SaCas9 coding sequence) and BB-m7-AC-m9 construct (self-inactivatingSaCas9 having target site inserted both in the AAV backbone and at theAC1 site of the SaCas9 coding sequence).

Incorporation by Reference

All publications, patents, and patent applications mentioned herein arehereby incorporated by reference in their entirety as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated by reference. In case ofconflict, the present application, including any definitions herein,will control.

Equivalents

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments described herein. Such equivalents are intended to beencompassed by the following claims.

What is claimed is:
 1. A transiently active genome editing system,comprising: a guide RNA (gRNA) comprising a targeting domain that iscomplementary to a eukaryotic nucleic acid sequence; and an engineeredRNA-guided nuclease encoded by a nucleic acid comprising the eukaryoticnucleotide sequence and a protospacer adjacent motif (PAM), wherein thePAM is recognized by the RNA-guided nuclease and is within or adjacentto the eukaryotic nucleotide sequence.
 2. The transiently active genomeediting system of claim 1, wherein the RNA-guided nuclease is a Cas9protein.
 3. The transiently active genome editing system of claim 2,wherein the engineered Cas9 protein and the gRNA form a Cas9/gRNAcomplex.
 4. The transiently active genome editing system of claim 3,wherein the Cas9/gRNA complex is adapted to cleave the nucleic acid. 5.The transiently active genome editing system of claim 2, wherein theengineered Cas9 protein comprises an amino acid insertion orsubstitution that is at least partially encoded by the eukaryoticnucleotide sequence.
 6. The transiently active genome editing system ofclaim 5, wherein the engineered Cas9 protein has at least about 80%nuclease activity of a wild-type Cas9 protein.
 7. The transiently activegenome editing system of claim 5, wherein the engineered Cas9 proteincomprises an amino acid insertion having a sequence of G-(X)6-10-G. 8.The transiently active genome editing system of claim 7, wherein theamino acid insertion, relative to SEQ ID NO: 2, is selected from thegroup consisting of: E271_N272insGX6-10G; L371_N372insGX6-10G; andQ737_A738insGX6-10G.
 9. The transiently active genome editing system ofclaim 5, wherein the engineered Cas9 protein comprises an amino acidinsertion, relative to SEQ ID NO: 2, at or near the N-terminus of a Cas9protein.
 10. The transiently active genome editing system of claim 2,wherein the engineered Cas9 protein comprises an amino acid sequencehaving at least 95% sequence identity to a sequence selected from thegroup consisting of SEQ ID NOs: 3-5 and
 10. 11. The transiently activegenome editing system of claim 2, wherein the engineered Cas9 protein isencoded by a nucleic acid comprising an insertion, relative to SEQ IDNO: 6, selected from the group consisting of: c.813_814insN24-36;c.1113_1114insN24-36; and c.2211_2212insN24-36.
 12. The transientlyactive genome editing system of claim 2, wherein the engineered Cas9protein is encoded by a nucleic acid comprising an insertion, relativeto SEQ ID NO: 6, at or near the N-terminus of a Cas9 protein codingsequence.
 13. The transiently active genome editing system of claim 2,wherein the engineered Cas9 protein is encoded by a nucleic acidcomprising a sequence having at least 95% sequence identity to asequence selected from the group consisting of SEQ ID NOs: 7-9 and 11.14. The transiently active genome editing system of claim 2, wherein theengineered Cas9 protein is an engineered S. aureus Cas9.
 15. Thetransiently active genome editing system of claim 1, wherein theRNA-guided nuclease is a Cpf1 protein.
 16. The transiently active genomeediting system of claim 15, wherein the engineered Cpf1 protein and thegRNA form a Cpf1/gRNA complex.
 17. The transiently active genome editingsystem of claim 16, wherein the Cpf1/gRNA complex is adapted to cleavethe nucleic acid.
 18. The transiently active genome editing system ofclaim 15, wherein the engineered Cpf1 protein comprises an amino acidinsertion or substitution that is at least partially encoded by theeukaryotic nucleotide sequence.
 19. The transiently active genomeediting system of claim 18, wherein the engineered Cpf1 protein has atleast about 80% nuclease activity of a wild-type Cpf1 protein.
 20. Thetransiently active genome editing system of claim 18, wherein theengineered Cpf1 protein comprises an amino acid insertion having asequence of G-(X)6-10-G.
 21. The transiently active genome editingsystem of claim 18, wherein the engineered Cpf1 protein comprises anamino acid insertion, relative to SEQ ID NO: 13, at a position selectedfrom the group consisting of between amino acid positions 147 and 148,anywhere between amino acid positions 484 and 492, anywhere betweenamino acid positions 568 and 590, anywhere between amino acid positions795 and 855, anywhere between amino acid positions 1131 and 1140, andanywhere between amino acid positions 1160 and
 1173. 22. The transientlyactive genome editing system of claim 18, wherein the Cpf1 proteincomprises an amino acid insertion, relative to SEQ ID NO: 13, at or nearthe N-terminus of the Cpf1 protein.
 23. The transiently active genomeediting system of claim 18, wherein the Cpf1 protein comprises an aminoacid sequence having at least 95% sequence identity to SEQ ID NO: 13.24. The transiently active genome editing system of claim 18, whereinthe Cpf1 protein comprises an amino acid insertion, relative to SEQ IDNO: 14, at a position selected from the group consisting of: betweennucleic acid positions 441 and 442, anywhere between nucleic acidpositions 1452 and 1474, anywhere between nucleic acid positions 1704and 1768, anywhere between nucleic acid positions 2385 and 2563,anywhere between nucleic acid positions 3393 and 3418, and anywherebetween nucleic acid positions 3480 and 3517, wherein the insertion doesnot alter the reading frame of the isolated nucleic acid.
 25. Thetransiently active genome editing system of claim 18, wherein the Cpf1protein comprises an amino acid insertion, relative to SEQ ID NO: 14, ator near the N-terminus of a Cpf1 protein coding sequence.
 26. Thetransiently active genome editing system of claim 18, wherein theengineered Cpf1 protein is encoded by a nucleic acid comprising asequence having at least 95% sequence identity to SEQ ID NO:
 14. 27. Thetransiently active genome editing system of claim 1, wherein the systemalters both a cellular endogenous target gene and the RNA-guidednuclease expression.
 28. The transiently active genome editing system ofclaim 1, wherein the eukaryotic nucleic acid sequence is at least 17nucleotides in length.
 29. The transiently active genome editing systemof claim 1, wherein the targeting domain of the gRNA is 16-24nucleotides in length.